Attachment 347841 Details for Bug 188747 – Patch

[patch] Patch

bug-188747-20180822135212.patch (text/plain), 149.62 KB, created by Jer Noble on 2018-08-22 13:52:13 PDT

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Creator: Jer Noble

Created: 2018-08-22 13:52:13 PDT

Size: 149.62 KB

patch

obsolete

>Subversion Revision: 235089
>diff --git a/Source/WTF/ChangeLog b/Source/WTF/ChangeLog
>index eac1685f75400fd21535b435f22da825030e45b8..da17134ad663a74a4ec10943ca11dc06609e0a33 100644
>--- a/Source/WTF/ChangeLog
>+++ b/Source/WTF/ChangeLog
>@@ -1,3 +1,14 @@
>+2018-08-22  Jer Noble  <jer.noble@apple.com>
>+
>+        Refactoring: eliminate raw pointer usage in Fullscreen code
>+        https://bugs.webkit.org/show_bug.cgi?id=188747
>+        <rdar://problem/43541164>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * WTF.xcodeproj/project.pbxproj:
>+        * wtf/WeakPtrContainer.h: Added.
>+
> 2018-08-19  Yusuke Suzuki  <yusukesuzuki@slowstart.org>
> 
>         [WTF] Add WTF::unalignedLoad and WTF::unalignedStore
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index 39fa429adf4e06361a0d19b5bbd907ac70bf5d27..f0cfa7dbd16aee9344b0c2f39df3979c83688041 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,164 @@
>+2018-08-22  Jer Noble  <jer.noble@apple.com>
>+
>+        Refactoring: eliminate raw pointer usage in Fullscreen code
>+        https://bugs.webkit.org/show_bug.cgi?id=188747
>+        <rdar://problem/43541164>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Two sources of raw pointers in the Fullscreen code:
>+        - Model classes (PlaybackSessionModel and VideoFullscreenModel) aren't ref-able, so
>+          they are passed around as raw references.
>+        - Observer classes (PlaybackSessionModelClient and VideoFullscreenModelClient, and
>+          VideoFullscreenChangeObserver) are also passed around as raw pointers, but shouldn't
>+          be ref-able.
>+
>+        Make Model classes ref-able by adding ref() and deref() which call virtual refModel and
>+        derefModel methods, overridden by implementing subclasses. Make every concrete observer
>+        inherit from CanMakeWeakPtr, and every registration method take WeakPtr wrappers around
>+        the client interface.
>+
>+        Since every Interface class now holds a strong reference to its Model classes, and each
>+        Model class holds a weak reference to all its clients, no explicit invalidate() method
>+        is necessary.
>+
>+        Notes:
>+
>+        - Since the weak pointer methods need to be able to downcast to the abstract base class,
>+          observers need to inherit publically (rather than privately) from those base classes.
>+        - Media element Models should compose EventListener rather than inheriting from it, since
>+          EventListener has its own RefCount.
>+        - WeakPtrs can't be held in HashSets (because they change value, and therefore hash, when
>+          their underlying object is destroyed), so clients should be stored in a Vector instead.
>+        - Interfaces should be given all required Refs at creation time, so that they can store
>+          those parameters as Refs instead of RefPtrs.
>+
>+        * platform/cocoa/PlaybackSessionInterface.h:
>+        (WebCore::PlaybackSessionInterface::~PlaybackSessionInterface): Deleted.
>+        * platform/cocoa/PlaybackSessionModel.h:
>+        (WebCore::PlaybackSessionModel::ref):
>+        (WebCore::PlaybackSessionModel::deref):
>+        (WebCore::PlaybackSessionModel::~PlaybackSessionModel): Deleted.
>+        * platform/cocoa/PlaybackSessionModelMediaElement.h:
>+        * platform/cocoa/PlaybackSessionModelMediaElement.mm:
>+        (WebCore::PlaybackSessionModelMediaElement::PlaybackSessionModelMediaElement):
>+        (WebCore::PlaybackSessionModelMediaElement::~PlaybackSessionModelMediaElement):
>+        (WebCore::PlaybackSessionModelMediaElement::setMediaElement):
>+        (WebCore::PlaybackSessionModelMediaElement::updateForEventName):
>+        (WebCore::PlaybackSessionModelMediaElement::addClient):
>+        (WebCore::PlaybackSessionModelMediaElement::removeClient):
>+        (WebCore::PlaybackSessionModelMediaElement::updateMediaSelectionOptions):
>+        (WebCore::PlaybackSessionModelMediaElement::updateMediaSelectionIndices):
>+        (WebCore::PlaybackSessionModelMediaElement::handleEvent): Deleted.
>+        * platform/cocoa/VideoFullscreenChangeObserver.h:
>+        (WebCore::VideoFullscreenChangeObserver::~VideoFullscreenChangeObserver): Deleted.
>+        * platform/cocoa/VideoFullscreenModel.h:
>+        (WebCore::VideoFullscreenModel::ref):
>+        (WebCore::VideoFullscreenModel::deref):
>+        (WebCore::VideoFullscreenModel::~VideoFullscreenModel): Deleted.
>+        * platform/cocoa/VideoFullscreenModelVideoElement.h:
>+        * platform/cocoa/VideoFullscreenModelVideoElement.mm:
>+        (VideoFullscreenModelVideoElement::VideoFullscreenModelVideoElement):
>+        (VideoFullscreenModelVideoElement::setVideoElement):
>+        (VideoFullscreenModelVideoElement::addClient):
>+        (VideoFullscreenModelVideoElement::removeClient):
>+        (VideoFullscreenModelVideoElement::setHasVideo):
>+        (VideoFullscreenModelVideoElement::setVideoDimensions):
>+        (VideoFullscreenModelVideoElement::willEnterPictureInPicture):
>+        (VideoFullscreenModelVideoElement::didEnterPictureInPicture):
>+        (VideoFullscreenModelVideoElement::failedToEnterPictureInPicture):
>+        (VideoFullscreenModelVideoElement::willExitPictureInPicture):
>+        (VideoFullscreenModelVideoElement::didExitPictureInPicture):
>+        (VideoFullscreenModelVideoElement::handleEvent): Deleted.
>+        * platform/ios/PlaybackSessionInterfaceAVKit.h:
>+        (WebCore::PlaybackSessionInterfaceAVKit::create):
>+        (WebCore::PlaybackSessionInterfaceAVKit::playbackSessionModel const):
>+        (): Deleted.
>+        * platform/ios/PlaybackSessionInterfaceAVKit.mm:
>+        (WebCore::PlaybackSessionInterfaceAVKit::PlaybackSessionInterfaceAVKit):
>+        (WebCore::PlaybackSessionInterfaceAVKit::~PlaybackSessionInterfaceAVKit):
>+        (WebCore::PlaybackSessionInterfaceAVKit::invalidate): Deleted.
>+        * platform/ios/VideoFullscreenInterfaceAVKit.h:
>+        * platform/ios/VideoFullscreenInterfaceAVKit.mm:
>+        (-[WebAVPlayerLayer layoutSublayers]):
>+        (-[WebAVPlayerLayer resolveBounds]):
>+        (-[WebAVPlayerLayer setVideoGravity:]):
>+        (VideoFullscreenInterfaceAVKit::create):
>+        (VideoFullscreenInterfaceAVKit::VideoFullscreenInterfaceAVKit):
>+        (VideoFullscreenInterfaceAVKit::~VideoFullscreenInterfaceAVKit):
>+        (VideoFullscreenInterfaceAVKit::setVideoFullscreenChangeObserver):
>+        (VideoFullscreenInterfaceAVKit::applicationDidBecomeActive):
>+        (VideoFullscreenInterfaceAVKit::setupFullscreen):
>+        (VideoFullscreenInterfaceAVKit::presentingViewController):
>+        (VideoFullscreenInterfaceAVKit::requestHideAndExitFullscreen):
>+        (VideoFullscreenInterfaceAVKit::preparedToExitFullscreen):
>+        (VideoFullscreenInterfaceAVKit::willStartPictureInPicture):
>+        (VideoFullscreenInterfaceAVKit::didStartPictureInPicture):
>+        (VideoFullscreenInterfaceAVKit::failedToStartPictureInPicture):
>+        (VideoFullscreenInterfaceAVKit::willStopPictureInPicture):
>+        (VideoFullscreenInterfaceAVKit::didStopPictureInPicture):
>+        (VideoFullscreenInterfaceAVKit::shouldExitFullscreenWithReason):
>+        (VideoFullscreenInterfaceAVKit::doSetup):
>+        (VideoFullscreenInterfaceAVKit::setMode):
>+        (VideoFullscreenInterfaceAVKit::clearMode):
>+        (VideoFullscreenInterfaceAVKit::setVideoFullscreenModel): Deleted.
>+        (VideoFullscreenInterfaceAVKit::invalidate): Deleted.
>+        * platform/ios/WebAVPlayerController.h:
>+        * platform/ios/WebAVPlayerController.mm:
>+        (-[WebAVPlayerController delegate]):
>+        (-[WebAVPlayerController playbackSessionInterface]):
>+        (-[WebAVPlayerController setPlaybackSessionInterface:]):
>+        * platform/ios/WebVideoFullscreenControllerAVKit.mm:
>+        (VideoFullscreenControllerContext::didCleanupFullscreen):
>+        (VideoFullscreenControllerContext::addClient):
>+        (VideoFullscreenControllerContext::removeClient):
>+        (VideoFullscreenControllerContext::willEnterPictureInPicture):
>+        (VideoFullscreenControllerContext::didEnterPictureInPicture):
>+        (VideoFullscreenControllerContext::failedToEnterPictureInPicture):
>+        (VideoFullscreenControllerContext::willExitPictureInPicture):
>+        (VideoFullscreenControllerContext::didExitPictureInPicture):
>+        (VideoFullscreenControllerContext::setUpFullscreen):
>+        * platform/mac/PlaybackSessionInterfaceMac.h:
>+        * platform/mac/PlaybackSessionInterfaceMac.mm:
>+        (WebCore::PlaybackSessionInterfaceMac::create):
>+        (WebCore::PlaybackSessionInterfaceMac::PlaybackSessionInterfaceMac):
>+        (WebCore::PlaybackSessionInterfaceMac::playbackSessionModel const):
>+        (WebCore::PlaybackSessionInterfaceMac::rateChanged):
>+        (WebCore::PlaybackSessionInterfaceMac::beginScrubbing):
>+        (WebCore::PlaybackSessionInterfaceMac::endScrubbing):
>+        (WebCore::PlaybackSessionInterfaceMac::setPlayBackControlsManager):
>+        (WebCore::PlaybackSessionInterfaceMac::updatePlaybackControlsManagerTiming):
>+        (WebCore::PlaybackSessionInterfaceMac::~PlaybackSessionInterfaceMac): Deleted.
>+        (WebCore::PlaybackSessionInterfaceMac::invalidate): Deleted.
>+        * platform/mac/VideoFullscreenInterfaceMac.h:
>+        (WebCore::VideoFullscreenInterfaceMac::create):
>+        (WebCore::VideoFullscreenInterfaceMac::videoFullscreenModel const):
>+        (WebCore::VideoFullscreenInterfaceMac::playbackSessionModel const):
>+        (WebCore::VideoFullscreenInterfaceMac::videoFullscreenChangeObserver const):
>+        * platform/mac/VideoFullscreenInterfaceMac.mm:
>+        (-[WebVideoFullscreenInterfaceMacObjC setUpPIPForVideoView:withFrame:inWindow:]):
>+        (-[WebVideoFullscreenInterfaceMacObjC boundsDidChangeForVideoViewContainer:]):
>+        (-[WebVideoFullscreenInterfaceMacObjC pipDidClose:]):
>+        (-[WebVideoFullscreenInterfaceMacObjC pipActionPlay:]):
>+        (-[WebVideoFullscreenInterfaceMacObjC pipActionPause:]):
>+        (-[WebVideoFullscreenInterfaceMacObjC pipActionStop:]):
>+        (WebCore::VideoFullscreenInterfaceMac::VideoFullscreenInterfaceMac):
>+        (WebCore::VideoFullscreenInterfaceMac::~VideoFullscreenInterfaceMac):
>+        (WebCore::VideoFullscreenInterfaceMac::setVideoFullscreenChangeObserver):
>+        (WebCore::VideoFullscreenInterfaceMac::setMode):
>+        (WebCore::VideoFullscreenInterfaceMac::clearMode):
>+        (WebCore::VideoFullscreenInterfaceMac::invalidate):
>+        (WebCore::VideoFullscreenInterfaceMac::requestHideAndExitPiP):
>+        (WebCore::VideoFullscreenInterfaceMac::setVideoFullscreenModel): Deleted.
>+        * platform/mac/WebPlaybackControlsManager.mm:
>+        (-[WebPlaybackControlsManager seekToTime:toleranceBefore:toleranceAfter:]):
>+        (-[WebPlaybackControlsManager setCurrentAudioTouchBarMediaSelectionOption:]):
>+        (-[WebPlaybackControlsManager setCurrentLegibleTouchBarMediaSelectionOption:]):
>+        (-[WebPlaybackControlsManager togglePlayback]):
>+        (-[WebPlaybackControlsManager setPlaying:]):
>+        (-[WebPlaybackControlsManager isPlaying]):
>+        (-[WebPlaybackControlsManager togglePictureInPicture]):
>+
> 2018-08-20  Jeremy Jones  <jeremyj@apple.com>
> 
>         UIWebView crashes while attempting to play youtube video on phone
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index 7ab364a65b01bfbf9ea342601135fa8f192c898a..46f792d0c4bd96ca72d6352b6afd3b20735a34cf 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,73 @@
>+2018-08-22  Jer Noble  <jer.noble@apple.com>
>+
>+        Refactoring: eliminate raw pointer usage in Fullscreen code
>+        https://bugs.webkit.org/show_bug.cgi?id=188747
>+        <rdar://problem/43541164>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Adopt those Ref and WeakPtr changes made in WebCore.
>+
>+        * UIProcess/Cocoa/PlaybackSessionManagerProxy.h:
>+        * UIProcess/Cocoa/PlaybackSessionManagerProxy.mm:
>+        (WebKit::PlaybackSessionModelContext::addClient):
>+        (WebKit::PlaybackSessionModelContext::removeClient):
>+        (WebKit::PlaybackSessionModelContext::durationChanged):
>+        (WebKit::PlaybackSessionModelContext::currentTimeChanged):
>+        (WebKit::PlaybackSessionModelContext::bufferedTimeChanged):
>+        (WebKit::PlaybackSessionModelContext::rateChanged):
>+        (WebKit::PlaybackSessionModelContext::seekableRangesChanged):
>+        (WebKit::PlaybackSessionModelContext::canPlayFastReverseChanged):
>+        (WebKit::PlaybackSessionModelContext::audioMediaSelectionOptionsChanged):
>+        (WebKit::PlaybackSessionModelContext::legibleMediaSelectionOptionsChanged):
>+        (WebKit::PlaybackSessionModelContext::audioMediaSelectionIndexChanged):
>+        (WebKit::PlaybackSessionModelContext::legibleMediaSelectionIndexChanged):
>+        (WebKit::PlaybackSessionModelContext::externalPlaybackChanged):
>+        (WebKit::PlaybackSessionModelContext::wirelessVideoPlaybackDisabledChanged):
>+        (WebKit::PlaybackSessionModelContext::mutedChanged):
>+        (WebKit::PlaybackSessionModelContext::volumeChanged):
>+        (WebKit::PlaybackSessionModelContext::pictureInPictureActiveChanged):
>+        (WebKit::PlaybackSessionManagerProxy::invalidate):
>+        (WebKit::PlaybackSessionManagerProxy::createModelAndInterface):
>+        (WebKit::PlaybackSessionManagerProxy::removeClientForContext):
>+        * UIProcess/Cocoa/VideoFullscreenManagerProxy.h:
>+        * UIProcess/Cocoa/VideoFullscreenManagerProxy.mm:
>+        (WebKit::VideoFullscreenModelContext::create):
>+        (WebKit::VideoFullscreenModelContext::VideoFullscreenModelContext):
>+        (WebKit::VideoFullscreenModelContext::addClient):
>+        (WebKit::VideoFullscreenModelContext::removeClient):
>+        (WebKit::VideoFullscreenModelContext::willEnterPictureInPicture):
>+        (WebKit::VideoFullscreenModelContext::didEnterPictureInPicture):
>+        (WebKit::VideoFullscreenModelContext::failedToEnterPictureInPicture):
>+        (WebKit::VideoFullscreenModelContext::willExitPictureInPicture):
>+        (WebKit::VideoFullscreenModelContext::didExitPictureInPicture):
>+        (WebKit::VideoFullscreenManagerProxy::invalidate):
>+        (WebKit::VideoFullscreenManagerProxy::createModelAndInterface):
>+        (WebKit::VideoFullscreenManagerProxy::removeClientForContext):
>+        (WebKit::VideoFullscreenModelContext::~VideoFullscreenModelContext): Deleted.
>+        * UIProcess/ios/fullscreen/WKFullScreenViewController.mm:
>+        (WKFullScreenViewControllerPlaybackSessionModelClient::setInterface):
>+        (WKFullScreenViewControllerVideoFullscreenModelClient::setInterface):
>+        (-[WKFullScreenViewController videoControlsManagerDidChange]):
>+        (-[WKFullScreenViewController _togglePiPAction:]):
>+        * UIProcess/mac/WKFullScreenWindowController.mm:
>+        (WebKit::WKFullScreenWindowControllerVideoFullscreenModelClient::setInterface):
>+        * WebProcess/cocoa/PlaybackSessionManager.h:
>+        * WebProcess/cocoa/PlaybackSessionManager.mm:
>+        (WebKit::PlaybackSessionInterfaceContext::PlaybackSessionInterfaceContext):
>+        (WebKit::PlaybackSessionManager::~PlaybackSessionManager):
>+        (WebKit::PlaybackSessionManager::createModelAndInterface):
>+        (WebKit::PlaybackSessionManager::removeContext):
>+        (WebKit::PlaybackSessionInterfaceContext::~PlaybackSessionInterfaceContext): Deleted.
>+        * WebProcess/cocoa/VideoFullscreenManager.h:
>+        (WebKit::VideoFullscreenInterfaceContext::create):
>+        (WebKit::VideoFullscreenInterfaceContext::createWeakPtr):
>+        * WebProcess/cocoa/VideoFullscreenManager.mm:
>+        (WebKit::VideoFullscreenInterfaceContext::VideoFullscreenInterfaceContext):
>+        (WebKit::VideoFullscreenManager::~VideoFullscreenManager):
>+        (WebKit::VideoFullscreenManager::createModelAndInterface):
>+        (WebKit::VideoFullscreenManager::removeContext):
>+
> 2018-08-20  Tim Horton  <timothy_horton@apple.com>
> 
>         Fix the iOSMac build with unified sources
>diff --git a/Source/WTF/WTF.xcodeproj/project.pbxproj b/Source/WTF/WTF.xcodeproj/project.pbxproj
>index 45b5ceaecf0e02ec5d65167787675c689d35245d..76f6cf9247dfe6c35bf7445a3d96bc60042f7a97 100644
>--- a/Source/WTF/WTF.xcodeproj/project.pbxproj
>+++ b/Source/WTF/WTF.xcodeproj/project.pbxproj
>@@ -605,6 +605,7 @@
> 		C4F8A93619C65EB400B2B15D /* Stopwatch.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Stopwatch.h; sourceTree = "<group>"; };
> 		C6F050790D9C432A99085E75 /* ASCIILiteral.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ASCIILiteral.cpp; sourceTree = "<group>"; };
> 		C8F597CA2A57417FBAB92FD6 /* RandomDevice.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = RandomDevice.cpp; sourceTree = "<group>"; };
>+		CD2D0D10212C76E60018C784 /* WeakPtrContainer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WeakPtrContainer.h; sourceTree = "<group>"; };
> 		CD5497AA15857D0300B5BC30 /* MediaTime.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = MediaTime.cpp; sourceTree = "<group>"; };
> 		CD5497AB15857D0300B5BC30 /* MediaTime.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MediaTime.h; sourceTree = "<group>"; };
> 		CD6D9FCD1EEF3AD4008B0671 /* Algorithms.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = Algorithms.h; sourceTree = "<group>"; };
>@@ -1136,6 +1137,7 @@
> 				0F66B2891DC97BAB004A1D3F /* WallTime.h */,
> 				83ABB3C020B3823200BA3306 /* WeakObjCPtr.h */,
> 				974CFC8D16A4F327006D5404 /* WeakPtr.h */,
>+				CD2D0D10212C76E60018C784 /* WeakPtrContainer.h */,
> 				0F3501631BB258C800F0A2A3 /* WeakRandom.h */,
> 				0FE4479A1B7AAA03009498EB /* WordLock.cpp */,
> 				0FE4479B1B7AAA03009498EB /* WordLock.h */,
>diff --git a/Source/WTF/wtf/WeakPtrContainer.h b/Source/WTF/wtf/WeakPtrContainer.h
>new file mode 100644
>index 0000000000000000000000000000000000000000..5340943a62420ed8adba8817111645825264f4e9
>--- /dev/null
>+++ b/Source/WTF/wtf/WeakPtrContainer.h
>@@ -0,0 +1,81 @@
>+/*
>+ * Copyright (C) 2018 Apple Inc. All rights reserved.
>+ *
>+ * Redistribution and use in source and binary forms, with or without
>+ * modification, are permitted provided that the following conditions
>+ * are met:
>+ * 1. Redistributions of source code must retain the above copyright
>+ *    notice, this list of conditions and the following disclaimer.
>+ * 2. Redistributions in binary form must reproduce the above copyright
>+ *    notice, this list of conditions and the following disclaimer in the
>+ *    documentation and/or other materials provided with the distribution.
>+ *
>+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
>+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
>+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
>+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
>+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
>+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
>+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
>+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
>+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
>+ * THE POSSIBILITY OF SUCH DAMAGE.
>+ */
>+
>+#pragma once
>+
>+#include <wtf/Vector.h>
>+#include <wtf/WeakPtr.h>
>+
>+namespace WTF {
>+
>+template <typename T>
>+class WeakPtrContainer {
>+public:
>+    void add(WeakPtr<T>&& ptr)
>+    {
>+        m_members.append(WTFMove(ptr));
>+    }
>+    
>+    void remove(T& ptr)
>+    {
>+        m_members.removeAll(&ptr);
>+    }
>+
>+    void clear()
>+    {
>+        m_members.clear();
>+    }
>+
>+    bool isEmpty() const
>+    {
>+        return m_members.isEmpty();
>+    }
>+    
>+    void removeNullMembers()
>+    {
>+        m_members.removeAllMatching([] (auto& ptr) { return !ptr; });
>+    }
>+    
>+    template <typename F>
>+    void forEachNonNullMember(F&& f)
>+    {
>+        bool hasNullMembers = false;
>+        for (auto& member : m_members) {
>+            if (member)
>+                f(*member);
>+            else
>+                hasNullMembers = true;
>+        }
>+        
>+        if (hasNullMembers)
>+            removeNullMembers();
>+    }
>+private:
>+    Vector<WeakPtr<T>> m_members;
>+};
>+
>+}
>+
>+using WTF::WeakPtrContainer;
>diff --git a/Source/WebCore/platform/cocoa/PlaybackSessionInterface.h b/Source/WebCore/platform/cocoa/PlaybackSessionInterface.h
>index cdf2bbfbddd7e2f935dc2b3cd49f55081884754b..db7b58fa9e045bb349554595f42c82029147098e 100644
>--- a/Source/WebCore/platform/cocoa/PlaybackSessionInterface.h
>+++ b/Source/WebCore/platform/cocoa/PlaybackSessionInterface.h
>@@ -27,16 +27,11 @@
> 
> #if PLATFORM(IOS) || (PLATFORM(MAC) && ENABLE(VIDEO_PRESENTATION_MODE))
> 
>-#include <wtf/Forward.h>
>-#include <wtf/Vector.h>
>-
> namespace WebCore {
> 
>-class TimeRanges;
>-
> class PlaybackSessionInterface {
> public:
>-    virtual ~PlaybackSessionInterface() { };
>+    virtual ~PlaybackSessionInterface() = default;
>     virtual void resetMediaState() = 0;
> };
> 
>diff --git a/Source/WebCore/platform/cocoa/PlaybackSessionModel.h b/Source/WebCore/platform/cocoa/PlaybackSessionModel.h
>index 1c4f0e3aee94113f70814ae850c84d44e77e2e99..08d82a4519a2ef6ec66a8344367f5f6a7d9f3319 100644
>--- a/Source/WebCore/platform/cocoa/PlaybackSessionModel.h
>+++ b/Source/WebCore/platform/cocoa/PlaybackSessionModel.h
>@@ -30,6 +30,7 @@
> #include <wtf/Forward.h>
> #include <wtf/Ref.h>
> #include <wtf/Vector.h>
>+#include <wtf/WeakPtr.h>
> 
> namespace WebCore {
> 
>@@ -39,8 +40,12 @@ struct MediaSelectionOption;
> 
> class PlaybackSessionModel {
> public:
>-    virtual ~PlaybackSessionModel() { };
>-    virtual void addClient(PlaybackSessionModelClient&) = 0;
>+    virtual ~PlaybackSessionModel() = default;
>+
>+    void ref() { refPlaybackSessionModel(); }
>+    void deref() { derefPlaybackSessionModel(); }
>+
>+    virtual void addClient(WeakPtr<PlaybackSessionModelClient>&&) = 0;
>     virtual void removeClient(PlaybackSessionModelClient&) = 0;
> 
>     virtual void play() = 0;
>@@ -84,6 +89,10 @@ public:
>     virtual bool isMuted() const = 0;
>     virtual double volume() const = 0;
>     virtual bool isPictureInPictureActive() const = 0;
>+
>+private:
>+    virtual void refPlaybackSessionModel() = 0;
>+    virtual void derefPlaybackSessionModel() = 0;
> };
> 
> class PlaybackSessionModelClient {
>diff --git a/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.h b/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.h
>index f5927dce035a7de7c0c6c9046e6d5b0204cac8d3..860de152a2240cd17eebb56f154e522d5b2a02d0 100644
>--- a/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.h
>+++ b/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.h
>@@ -30,9 +30,8 @@
> #include "EventListener.h"
> #include "HTMLMediaElementEnums.h"
> #include "PlaybackSessionModel.h"
>-#include <wtf/HashSet.h>
> #include <wtf/RefPtr.h>
>-#include <wtf/Vector.h>
>+#include <wtf/WeakPtrContainer.h>
> 
> namespace WebCore {
> 
>@@ -41,7 +40,10 @@ class HTMLMediaElement;
> class TextTrack;
> class PlaybackSessionInterface;
> 
>-class PlaybackSessionModelMediaElement final : public PlaybackSessionModel, public EventListener {
>+class PlaybackSessionModelMediaElement final
>+    : public RefCounted<PlaybackSessionModelMediaElement>
>+    , public CanMakeWeakPtr<PlaybackSessionModelMediaElement>
>+    , public PlaybackSessionModel {
> public:
>     static Ref<PlaybackSessionModelMediaElement> create()
>     {
>@@ -51,11 +53,9 @@ public:
>     WEBCORE_EXPORT void setMediaElement(HTMLMediaElement*);
>     HTMLMediaElement* mediaElement() const { return m_mediaElement.get(); }
> 
>-    WEBCORE_EXPORT void handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event&) final;
>     void updateForEventName(const WTF::AtomicString&);
>-    bool operator==(const EventListener& rhs) const final { return static_cast<const WebCore::EventListener*>(this) == &rhs; }
> 
>-    WEBCORE_EXPORT void addClient(PlaybackSessionModelClient&);
>+    WEBCORE_EXPORT void addClient(WeakPtr<PlaybackSessionModelClient>&&);
>     WEBCORE_EXPORT void removeClient(PlaybackSessionModelClient&);
>     WEBCORE_EXPORT void play() final;
>     WEBCORE_EXPORT void pause() final;
>@@ -96,19 +96,27 @@ public:
>     double volume() const final;
>     bool isPictureInPictureActive() const final;
> 
>+    using RefCounted::ref;
>+    using RefCounted::deref;
>+
> protected:
>     WEBCORE_EXPORT PlaybackSessionModelMediaElement();
> 
> private:
>+    void refPlaybackSessionModel() final { ref(); }
>+    void derefPlaybackSessionModel() final { deref(); }
>+    
>     void progressEventTimerFired();
>     static const Vector<WTF::AtomicString>& observedEventNames();
>     const WTF::AtomicString& eventNameAll();
> 
>+    class MediaElementEventListener;
>+
>     RefPtr<HTMLMediaElement> m_mediaElement;
>-    bool m_isListening { false };
>-    HashSet<PlaybackSessionModelClient*> m_clients;
>+    WeakPtrContainer<PlaybackSessionModelClient> m_clients;
>     Vector<RefPtr<TextTrack>> m_legibleTracksForMenu;
>     Vector<RefPtr<AudioTrack>> m_audioTracksForMenu;
>+    Ref<MediaElementEventListener> m_eventListener;
> 
>     double playbackStartedTime() const;
>     void updateMediaSelectionOptions();
>diff --git a/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.mm b/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.mm
>index a11b70c1ed296ce0cd1ec1798df61d17fd0273d7..5e973009cf61de5815850ee081594f18ef40ce32 100644
>--- a/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.mm
>+++ b/Source/WebCore/platform/cocoa/PlaybackSessionModelMediaElement.mm
>@@ -46,14 +46,34 @@
> #import <wtf/SoftLinking.h>
> 
> namespace WebCore {
>+    
>+class PlaybackSessionModelMediaElement::MediaElementEventListener final : public EventListener {
>+public:
>+    MediaElementEventListener(WeakPtr<PlaybackSessionModelMediaElement>&& parent)
>+        : EventListener(CPPEventListenerType)
>+        , m_parent(WTFMove(parent))
>+    {
>+    }
>+private:
>+    void handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event& event) final
>+    {
>+        if (m_parent)
>+            m_parent->updateForEventName(event.type());
>+    }
>+    bool operator==(const EventListener& rhs) const final { return static_cast<const WebCore::EventListener*>(this) == &rhs; }
>+
>+    WeakPtr<PlaybackSessionModelMediaElement> m_parent;
>+};
> 
> PlaybackSessionModelMediaElement::PlaybackSessionModelMediaElement()
>-    : EventListener(EventListener::CPPEventListenerType)
>+    : m_eventListener(adoptRef(*new MediaElementEventListener(makeWeakPtr(*this))))
> {
> }
> 
> PlaybackSessionModelMediaElement::~PlaybackSessionModelMediaElement()
> {
>+    m_clients.clear();
>+    setMediaElement(nullptr);
> }
> 
> void PlaybackSessionModelMediaElement::setMediaElement(HTMLMediaElement* mediaElement)
>@@ -63,51 +83,43 @@ void PlaybackSessionModelMediaElement::setMediaElement(HTMLMediaElement* mediaEl
> 
>     auto& events = eventNames();
> 
>-    if (m_mediaElement && m_isListening) {
>+    if (m_mediaElement) {
>         for (auto& eventName : observedEventNames())
>-            m_mediaElement->removeEventListener(eventName, *this, false);
>+            m_mediaElement->removeEventListener(eventName, m_eventListener.copyRef(), false);
>         if (auto* audioTracks = m_mediaElement->audioTracks()) {
>-            audioTracks->removeEventListener(events.addtrackEvent, *this, false);
>-            audioTracks->removeEventListener(events.changeEvent, *this, false);
>-            audioTracks->removeEventListener(events.removetrackEvent, *this, false);
>+            audioTracks->removeEventListener(events.addtrackEvent, m_eventListener.copyRef(), false);
>+            audioTracks->removeEventListener(events.changeEvent, m_eventListener.copyRef(), false);
>+            audioTracks->removeEventListener(events.removetrackEvent, m_eventListener.copyRef(), false);
>         }
> 
>         if (auto* textTracks = m_mediaElement->audioTracks()) {
>-            textTracks->removeEventListener(events.addtrackEvent, *this, false);
>-            textTracks->removeEventListener(events.changeEvent, *this, false);
>-            textTracks->removeEventListener(events.removetrackEvent, *this, false);
>+            textTracks->removeEventListener(events.addtrackEvent, m_eventListener.copyRef(), false);
>+            textTracks->removeEventListener(events.changeEvent, m_eventListener.copyRef(), false);
>+            textTracks->removeEventListener(events.removetrackEvent, m_eventListener.copyRef(), false);
>         }
>-    }
>-    m_isListening = false;
>-
>-    if (m_mediaElement)
>         m_mediaElement->resetPlaybackSessionState();
>+    }
> 
>     m_mediaElement = mediaElement;
> 
>     if (m_mediaElement) {
>         for (auto& eventName : observedEventNames())
>-            m_mediaElement->addEventListener(eventName, *this, false);
>+            m_mediaElement->addEventListener(eventName, m_eventListener.copyRef(), false);
> 
>         auto& audioTracks = m_mediaElement->ensureAudioTracks();
>-        audioTracks.addEventListener(events.addtrackEvent, *this, false);
>-        audioTracks.addEventListener(events.changeEvent, *this, false);
>-        audioTracks.addEventListener(events.removetrackEvent, *this, false);
>+        audioTracks.addEventListener(events.addtrackEvent, m_eventListener.copyRef(), false);
>+        audioTracks.addEventListener(events.changeEvent, m_eventListener.copyRef(), false);
>+        audioTracks.addEventListener(events.removetrackEvent, m_eventListener.copyRef(), false);
> 
>         auto& textTracks = m_mediaElement->ensureTextTracks();
>-        textTracks.addEventListener(events.addtrackEvent, *this, false);
>-        textTracks.addEventListener(events.changeEvent, *this, false);
>-        textTracks.addEventListener(events.removetrackEvent, *this, false);
>+        textTracks.addEventListener(events.addtrackEvent, m_eventListener.copyRef(), false);
>+        textTracks.addEventListener(events.changeEvent, m_eventListener.copyRef(), false);
>+        textTracks.addEventListener(events.removetrackEvent, m_eventListener.copyRef(), false);
>     }
> 
>     updateForEventName(eventNameAll());
> }
> 
>-void PlaybackSessionModelMediaElement::handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event& event)
>-{
>-    updateForEventName(event.type());
>-}
>-
> void PlaybackSessionModelMediaElement::updateForEventName(const WTF::AtomicString& eventName)
> {
>     if (m_clients.isEmpty())
>@@ -117,51 +129,46 @@ void PlaybackSessionModelMediaElement::updateForEventName(const WTF::AtomicStrin
> 
>     if (all
>         || eventName == eventNames().durationchangeEvent) {
>-        double duration = this->duration();
>-        for (auto client : m_clients)
>-            client->durationChanged(duration);
>+        m_clients.forEachNonNullMember([duration = duration()] (auto& client) {
>+            client.durationChanged(duration);
>+        });
>         // These is no standard event for minFastReverseRateChange; duration change is a reasonable proxy for it.
>         // It happens every time a new item becomes ready to play.
>-        bool canPlayFastReverse = this->canPlayFastReverse();
>-        for (auto client : m_clients)
>-            client->canPlayFastReverseChanged(canPlayFastReverse);
>+        m_clients.forEachNonNullMember([canPlayFastReverse = canPlayFastReverse()] (auto& client) {
>+            client.canPlayFastReverseChanged(canPlayFastReverse);
>+        });
>     }
> 
>     if (all
>         || eventName == eventNames().playEvent
>         || eventName == eventNames().playingEvent) {
>-        for (auto client : m_clients)
>-            client->playbackStartedTimeChanged(playbackStartedTime());
>+        m_clients.forEachNonNullMember([playbackStartedTime = playbackStartedTime()] (auto& client) {
>+            client.playbackStartedTimeChanged(playbackStartedTime);
>+        });
>     }
> 
>     if (all
>         || eventName == eventNames().pauseEvent
>         || eventName == eventNames().playEvent
>         || eventName == eventNames().ratechangeEvent) {
>-        bool isPlaying = this->isPlaying();
>-        float playbackRate = this->playbackRate();
>-        for (auto client : m_clients)
>-            client->rateChanged(isPlaying, playbackRate);
>+        m_clients.forEachNonNullMember([isPlaying = isPlaying(), playbackRate = playbackRate()] (auto& client) {
>+            client.rateChanged(isPlaying, playbackRate);
>+        });
>     }
> 
>     if (all
>         || eventName == eventNames().timeupdateEvent) {
>-        auto currentTime = this->currentTime();
>-        auto anchorTime = [[NSProcessInfo processInfo] systemUptime];
>-        for (auto client : m_clients)
>-            client->currentTimeChanged(currentTime, anchorTime);
>+        m_clients.forEachNonNullMember([currentTime = currentTime(), anchorTime = [[NSProcessInfo processInfo] systemUptime]] (auto& client) {
>+            client.currentTimeChanged(currentTime, anchorTime);
>+        });
>     }
> 
>     if (all
>         || eventName == eventNames().progressEvent) {
>-        auto bufferedTime = this->bufferedTime();
>-        auto seekableRanges = this->seekableRanges();
>-        auto seekableTimeRangesLastModifiedTime = this->seekableTimeRangesLastModifiedTime();
>-        auto liveUpdateInterval = this->liveUpdateInterval();
>-        for (auto client : m_clients) {
>-            client->bufferedTimeChanged(bufferedTime);
>-            client->seekableRangesChanged(seekableRanges, seekableTimeRangesLastModifiedTime, liveUpdateInterval);
>-        }
>+        m_clients.forEachNonNullMember([bufferedTime = bufferedTime(), seekableRanges = seekableRanges(), seekableTimeRangesLastModifiedTime = seekableTimeRangesLastModifiedTime(), liveUpdateInterval = liveUpdateInterval()] (auto& client) {
>+            client.bufferedTimeChanged(bufferedTime);
>+            client.seekableRangesChanged(seekableRanges, seekableTimeRangesLastModifiedTime, liveUpdateInterval);
>+        });
>     }
> 
>     if (all
>@@ -171,24 +178,17 @@ void PlaybackSessionModelMediaElement::updateForEventName(const WTF::AtomicStrin
> 
>     if (all
>         || eventName == eventNames().webkitcurrentplaybacktargetiswirelesschangedEvent) {
>-        bool enabled = externalPlaybackEnabled();
>-        ExternalPlaybackTargetType targetType = externalPlaybackTargetType();
>-        String localizedDeviceName = externalPlaybackLocalizedDeviceName();
>-
>-        bool wirelessVideoPlaybackDisabled = this->wirelessVideoPlaybackDisabled();
>-
>-        for (auto client : m_clients) {
>-            client->externalPlaybackChanged(enabled, targetType, localizedDeviceName);
>-            client->wirelessVideoPlaybackDisabledChanged(wirelessVideoPlaybackDisabled);
>-        }
>+        m_clients.forEachNonNullMember([enabled = externalPlaybackEnabled(), targetType = externalPlaybackTargetType(), localizedDeviceName = externalPlaybackLocalizedDeviceName(), wirelessVideoPlaybackDisabled = wirelessVideoPlaybackDisabled()] (auto& client) {
>+            client.externalPlaybackChanged(enabled, targetType, localizedDeviceName);
>+            client.wirelessVideoPlaybackDisabledChanged(wirelessVideoPlaybackDisabled);
>+        });
>     }
> 
>     if (all
>         || eventName == eventNames().webkitpresentationmodechangedEvent) {
>-        bool isPictureInPictureActive = this->isPictureInPictureActive();
>-
>-        for (auto client : m_clients)
>-            client->pictureInPictureActiveChanged(isPictureInPictureActive);
>+        m_clients.forEachNonNullMember([isPictureInPictureActive = isPictureInPictureActive()] (auto& client) {
>+            client.pictureInPictureActiveChanged(isPictureInPictureActive);
>+        });
>     }
> 
> 
>@@ -199,22 +199,20 @@ void PlaybackSessionModelMediaElement::updateForEventName(const WTF::AtomicStrin
> 
>     if (all
>         || eventName == eventNames().volumechangeEvent) {
>-        for (auto client : m_clients) {
>-            client->mutedChanged(isMuted());
>-            client->volumeChanged(volume());
>-        }
>+        m_clients.forEachNonNullMember([isMuted = isMuted(), volume = volume()] (auto& client) {
>+            client.mutedChanged(isMuted);
>+            client.volumeChanged(volume);
>+        });
>     }
> }
>-void PlaybackSessionModelMediaElement::addClient(PlaybackSessionModelClient& client)
>+void PlaybackSessionModelMediaElement::addClient(WeakPtr<PlaybackSessionModelClient>&& client)
> {
>-    ASSERT(!m_clients.contains(&client));
>-    m_clients.add(&client);
>+    m_clients.add(WTFMove(client));
> }
> 
> void PlaybackSessionModelMediaElement::removeClient(PlaybackSessionModelClient& client)
> {
>-    ASSERT(m_clients.contains(&client));
>-    m_clients.remove(&client);
>+    m_clients.remove(client);
> }
> 
> void PlaybackSessionModelMediaElement::play()
>@@ -346,26 +344,18 @@ void PlaybackSessionModelMediaElement::updateMediaSelectionOptions()
>     else
>         m_audioTracksForMenu.clear();
> 
>-    auto audioOptions = audioMediaSelectionOptions();
>-    auto audioIndex = audioMediaSelectedIndex();
>-    auto legibleOptions = legibleMediaSelectionOptions();
>-    auto legibleIndex = legibleMediaSelectedIndex();
>-
>-    for (auto client : m_clients) {
>-        client->audioMediaSelectionOptionsChanged(audioOptions, audioIndex);
>-        client->legibleMediaSelectionOptionsChanged(legibleOptions, legibleIndex);
>-    }
>+    m_clients.forEachNonNullMember([audioOptions = audioMediaSelectionOptions(), audioIndex = audioMediaSelectedIndex(), legibleOptions = legibleMediaSelectionOptions(), legibleIndex = legibleMediaSelectedIndex()] (auto& client) {
>+        client.audioMediaSelectionOptionsChanged(audioOptions, audioIndex);
>+        client.legibleMediaSelectionOptionsChanged(legibleOptions, legibleIndex);
>+    });
> }
> 
> void PlaybackSessionModelMediaElement::updateMediaSelectionIndices()
> {
>-    auto audioIndex = audioMediaSelectedIndex();
>-    auto legibleIndex = legibleMediaSelectedIndex();
>-
>-    for (auto client : m_clients) {
>-        client->audioMediaSelectionIndexChanged(audioIndex);
>-        client->legibleMediaSelectionIndexChanged(legibleIndex);
>-    }
>+    m_clients.forEachNonNullMember([audioIndex = audioMediaSelectedIndex(), legibleIndex = legibleMediaSelectedIndex()] (auto& client) {
>+        client.audioMediaSelectionIndexChanged(audioIndex);
>+        client.legibleMediaSelectionIndexChanged(legibleIndex);
>+    });
> }
> 
> double PlaybackSessionModelMediaElement::playbackStartedTime() const
>diff --git a/Source/WebCore/platform/cocoa/VideoFullscreenChangeObserver.h b/Source/WebCore/platform/cocoa/VideoFullscreenChangeObserver.h
>index 4eb0580c96139dd47e75812e619bc905d6b76ed5..4990813a3909e602cf5566a897f8707194dd6b9b 100644
>--- a/Source/WebCore/platform/cocoa/VideoFullscreenChangeObserver.h
>+++ b/Source/WebCore/platform/cocoa/VideoFullscreenChangeObserver.h
>@@ -32,7 +32,7 @@ namespace WebCore {
> 
> class VideoFullscreenChangeObserver {
> public:
>-    virtual ~VideoFullscreenChangeObserver() { };
>+    virtual ~VideoFullscreenChangeObserver() = default;
>     virtual void requestUpdateInlineRect() = 0;
>     virtual void requestVideoContentLayer() = 0;
>     virtual void returnVideoContentLayer() = 0;
>diff --git a/Source/WebCore/platform/cocoa/VideoFullscreenModel.h b/Source/WebCore/platform/cocoa/VideoFullscreenModel.h
>index ce513541642ffba32f7db6b8037b60b8007d1eed..6d1b7e98a9e35b67a2c371cba60afc388b6ab5be 100644
>--- a/Source/WebCore/platform/cocoa/VideoFullscreenModel.h
>+++ b/Source/WebCore/platform/cocoa/VideoFullscreenModel.h
>@@ -30,7 +30,7 @@
> 
> #include "FloatRect.h"
> #include "HTMLMediaElementEnums.h"
>-#include "PlaybackSessionModel.h"
>+#include <wtf/WeakPtr.h>
> 
> #if PLATFORM(IOS)
> OBJC_CLASS AVPlayerViewController;
>@@ -43,8 +43,15 @@ class VideoFullscreenModelClient;
> 
> class VideoFullscreenModel {
> public:
>-    virtual ~VideoFullscreenModel() { };
>-    virtual void addClient(VideoFullscreenModelClient&) = 0;
>+    virtual ~VideoFullscreenModel() = default;
>+
>+    void ref() { refVideoFullscreenModel(); }
>+    void deref() { derefVideoFullscreenModel(); }
>+
>+    virtual void refVideoFullscreenModel() = 0;
>+    virtual void derefVideoFullscreenModel() = 0;
>+
>+    virtual void addClient(WeakPtr<VideoFullscreenModelClient>&&) = 0;
>     virtual void removeClient(VideoFullscreenModelClient&)= 0;
> 
>     virtual void requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenMode, bool finishedWithMedia = false) = 0;
>diff --git a/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.h b/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.h
>index 037dd02b61d3b1a824b3f9c0ec161d599f310de7..8268da5a024371d1ddfbba182196035ad95b53e4 100644
>--- a/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.h
>+++ b/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.h
>@@ -28,16 +28,14 @@
> 
> #if PLATFORM(IOS) || (PLATFORM(MAC) && ENABLE(VIDEO_PRESENTATION_MODE))
> 
>-#include "EventListener.h"
> #include "FloatRect.h"
> #include "HTMLMediaElementEnums.h"
> #include "PlatformLayer.h"
> #include "VideoFullscreenModel.h"
> #include <wtf/Function.h>
>-#include <wtf/HashSet.h>
> #include <wtf/RefPtr.h>
> #include <wtf/RetainPtr.h>
>-#include <wtf/Vector.h>
>+#include <wtf/WeakPtrContainer.h>
> 
> namespace WebCore {
> class AudioTrack;
>@@ -45,7 +43,10 @@ class HTMLVideoElement;
> class TextTrack;
> class PlaybackSessionModelMediaElement;
> 
>-class VideoFullscreenModelVideoElement : public VideoFullscreenModel, public EventListener {
>+class VideoFullscreenModelVideoElement 
>+    : public RefCounted<VideoFullscreenModelVideoElement>
>+    , public CanMakeWeakPtr<VideoFullscreenModelVideoElement>
>+    , public VideoFullscreenModel {
> public:
>     static RefPtr<VideoFullscreenModelVideoElement> create()
>     {
>@@ -58,11 +59,9 @@ public:
>     WEBCORE_EXPORT void willExitFullscreen();
>     WEBCORE_EXPORT void waitForPreparedForInlineThen(WTF::Function<void()>&& completionHandler = [] { });
>     
>-    WEBCORE_EXPORT void handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event&) override;
>     void updateForEventName(const WTF::AtomicString&);
>-    bool operator==(const EventListener& rhs) const override { return static_cast<const WebCore::EventListener*>(this) == &rhs; }
> 
>-    WEBCORE_EXPORT void addClient(VideoFullscreenModelClient&) override;
>+    WEBCORE_EXPORT void addClient(WeakPtr<VideoFullscreenModelClient>&&) override;
>     WEBCORE_EXPORT void removeClient(VideoFullscreenModelClient&) override;
>     WEBCORE_EXPORT void requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenMode, bool finishedWithMedia = false) override;
>     WEBCORE_EXPORT void setVideoLayerFrame(FloatRect) override;
>@@ -72,6 +71,8 @@ public:
>     FloatSize videoDimensions() const override { return m_videoDimensions; }
>     bool hasVideo() const override { return m_hasVideo; }
> 
>+    using RefCounted::ref;
>+    using RefCounted::deref;
> 
> protected:
>     WEBCORE_EXPORT VideoFullscreenModelVideoElement();
>@@ -80,6 +81,8 @@ private:
>     void setHasVideo(bool);
>     void setVideoDimensions(const FloatSize&);
> 
>+    void refVideoFullscreenModel() final { ref(); }
>+    void derefVideoFullscreenModel() final { deref(); }
>     void willEnterPictureInPicture() override;
>     void didEnterPictureInPicture() override;
>     void failedToEnterPictureInPicture() override;
>@@ -89,15 +92,17 @@ private:
>     static const Vector<WTF::AtomicString>& observedEventNames();
>     const WTF::AtomicString& eventNameAll();
> 
>+    class MediaElementEventListener;
>+
>     RefPtr<HTMLVideoElement> m_videoElement;
>     RetainPtr<PlatformLayer> m_videoFullscreenLayer;
>-    bool m_isListening { false };
>-    HashSet<VideoFullscreenModelClient*> m_clients;
>+    WeakPtrContainer<VideoFullscreenModelClient> m_clients;
>     bool m_hasVideo { false };
>     FloatSize m_videoDimensions;
>     FloatRect m_videoFrame;
>     Vector<RefPtr<TextTrack>> m_legibleTracksForMenu;
>     Vector<RefPtr<AudioTrack>> m_audioTracksForMenu;
>+    Ref<MediaElementEventListener> m_eventListener;
> };
> 
> }
>diff --git a/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.mm b/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.mm
>index c0a4fa5f0eb5af0f87f585dcca5d65706a7f504e..a861cc7fd1bd6b7d72177b8bbe518546f574d75c 100644
>--- a/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.mm
>+++ b/Source/WebCore/platform/cocoa/VideoFullscreenModelVideoElement.mm
>@@ -47,8 +47,27 @@
> 
> using namespace WebCore;
> 
>+
>+class VideoFullscreenModelVideoElement::MediaElementEventListener final : public EventListener {
>+public:
>+    MediaElementEventListener(WeakPtr<VideoFullscreenModelVideoElement>&& parent)
>+        : EventListener(CPPEventListenerType)
>+        , m_parent(WTFMove(parent))
>+    {
>+    }
>+private:
>+    void handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event& event) final
>+    {
>+        if (m_parent)
>+            m_parent->updateForEventName(event.type());
>+    }
>+    bool operator==(const EventListener& rhs) const final { return static_cast<const WebCore::EventListener*>(this) == &rhs; }
>+
>+    WeakPtr<VideoFullscreenModelVideoElement> m_parent;
>+};
>+
> VideoFullscreenModelVideoElement::VideoFullscreenModelVideoElement()
>-    : EventListener(EventListener::CPPEventListenerType)
>+    : m_eventListener(adoptRef(*new MediaElementEventListener(makeWeakPtr(*this))))
> {
> }
> 
>@@ -64,28 +83,21 @@ void VideoFullscreenModelVideoElement::setVideoElement(HTMLVideoElement* videoEl
>     if (m_videoElement && m_videoElement->videoFullscreenLayer())
>         m_videoElement->setVideoFullscreenLayer(nullptr);
> 
>-    if (m_videoElement && m_isListening) {
>+    if (m_videoElement) {
>         for (auto& eventName : observedEventNames())
>-            m_videoElement->removeEventListener(eventName, *this, false);
>+            m_videoElement->removeEventListener(eventName, m_eventListener.copyRef(), false);
>     }
>-    m_isListening = false;
> 
>     m_videoElement = videoElement;
> 
>     if (m_videoElement) {
>         for (auto& eventName : observedEventNames())
>-            m_videoElement->addEventListener(eventName, *this, false);
>-        m_isListening = true;
>+            m_videoElement->addEventListener(eventName, m_eventListener.copyRef(), false);
>     }
> 
>     updateForEventName(eventNameAll());
> }
> 
>-void VideoFullscreenModelVideoElement::handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event& event)
>-{
>-    updateForEventName(event.type());
>-}
>-
> void VideoFullscreenModelVideoElement::updateForEventName(const WTF::AtomicString& eventName)
> {
>     if (m_clients.isEmpty())
>@@ -195,16 +207,14 @@ void VideoFullscreenModelVideoElement::fullscreenModeChanged(HTMLMediaElementEnu
>         m_videoElement->fullscreenModeChanged(videoFullscreenMode);
> }
> 
>-void VideoFullscreenModelVideoElement::addClient(VideoFullscreenModelClient& client)
>+void VideoFullscreenModelVideoElement::addClient(WeakPtr<VideoFullscreenModelClient>&& client)
> {
>-    ASSERT(!m_clients.contains(&client));
>-    m_clients.add(&client);
>+    m_clients.add(WTFMove(client));
> }
> 
> void VideoFullscreenModelVideoElement::removeClient(VideoFullscreenModelClient& client)
> {
>-    ASSERT(m_clients.contains(&client));
>-    m_clients.remove(&client);
>+    m_clients.remove(client);
> }
> 
> bool VideoFullscreenModelVideoElement::isVisible() const
>@@ -225,8 +235,9 @@ void VideoFullscreenModelVideoElement::setHasVideo(bool hasVideo)
> 
>     m_hasVideo = hasVideo;
> 
>-    for (auto& client : m_clients)
>-        client->hasVideoChanged(m_hasVideo);
>+    m_clients.forEachNonNullMember([hasVideo] (auto& client) {
>+        client.hasVideoChanged(hasVideo);
>+    });
> }
> 
> void VideoFullscreenModelVideoElement::setVideoDimensions(const FloatSize& videoDimensions)
>@@ -236,38 +247,44 @@ void VideoFullscreenModelVideoElement::setVideoDimensions(const FloatSize& video
> 
>     m_videoDimensions = videoDimensions;
> 
>-    for (auto& client : m_clients)
>-        client->videoDimensionsChanged(m_videoDimensions);
>+    m_clients.forEachNonNullMember([videoDimensions] (auto& client) {
>+        client.videoDimensionsChanged(videoDimensions);
>+    });
> }
> 
> void VideoFullscreenModelVideoElement::willEnterPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->willEnterPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.willEnterPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelVideoElement::didEnterPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->didEnterPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.didEnterPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelVideoElement::failedToEnterPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->failedToEnterPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.failedToEnterPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelVideoElement::willExitPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->willExitPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.willExitPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelVideoElement::didExitPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->didExitPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.didExitPictureInPicture();
>+    });
> }
> 
> #endif
>diff --git a/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.h b/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.h
>index 85801915e0f019680df47c816c0bddb5b60bc393..42230189034504e3781c97464ff16160dd1e082d 100644
>--- a/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.h
>+++ b/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.h
>@@ -51,18 +51,17 @@ class IntRect;
> class PlaybackSessionModel;
> class WebPlaybackSessionChangeObserver;
> 
>-class WEBCORE_EXPORT PlaybackSessionInterfaceAVKit
>+class PlaybackSessionInterfaceAVKit
>     : public PlaybackSessionInterface
>     , public PlaybackSessionModelClient
>     , public RefCounted<PlaybackSessionInterfaceAVKit> {
>-
> public:
>-    static Ref<PlaybackSessionInterfaceAVKit> create(PlaybackSessionModel& model)
>+    static Ref<PlaybackSessionInterfaceAVKit> create(Ref<PlaybackSessionModel>&& model)
>     {
>-        return adoptRef(*new PlaybackSessionInterfaceAVKit(model));
>+        return adoptRef(*new PlaybackSessionInterfaceAVKit(WTFMove(model)));
>     }
>     virtual ~PlaybackSessionInterfaceAVKit();
>-    PlaybackSessionModel* playbackSessionModel() const { return m_playbackSessionModel; }
>+    PlaybackSessionModel& playbackSessionModel() const { return m_playbackSessionModel; }
> 
>     // PlaybackSessionInterface
>     WEBCORE_EXPORT void resetMediaState() override;
>@@ -81,15 +80,14 @@ public:
>     WEBCORE_EXPORT void mutedChanged(bool) override;
>     WEBCORE_EXPORT void volumeChanged(double) override;
> 
>-    WEBCORE_EXPORT virtual void invalidate();
>-
>     WebAVPlayerController *playerController() const { return m_playerController.get(); }
> 
> protected:
>-    WEBCORE_EXPORT PlaybackSessionInterfaceAVKit(PlaybackSessionModel&);
>+    WEBCORE_EXPORT PlaybackSessionInterfaceAVKit(Ref<PlaybackSessionModel>&&);
> 
>     RetainPtr<WebAVPlayerController> m_playerController;
>-    PlaybackSessionModel* m_playbackSessionModel { nullptr };
>+    Ref<PlaybackSessionModel> m_playbackSessionModel;
>+    WeakPtrFactory<PlaybackSessionModelClient> m_weakPtrFactory;
> };
> 
> }
>diff --git a/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.mm b/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.mm
>index 0a28548b7f5951619534432da9a0007ddb9ae864..da03ebe22d3d441ebe28f38f3cce428843fae427 100644
>--- a/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.mm
>+++ b/Source/WebCore/platform/ios/PlaybackSessionInterfaceAVKit.mm
>@@ -49,32 +49,30 @@ SOFT_LINK_CLASS_OPTIONAL(AVKit, AVValueTiming)
> namespace WebCore {
> using namespace PAL;
> 
>-PlaybackSessionInterfaceAVKit::PlaybackSessionInterfaceAVKit(PlaybackSessionModel& model)
>+PlaybackSessionInterfaceAVKit::PlaybackSessionInterfaceAVKit(Ref<PlaybackSessionModel>&& model)
>     : m_playerController(adoptNS([[WebAVPlayerController alloc] init]))
>-    , m_playbackSessionModel(&model)
>+    , m_playbackSessionModel(WTFMove(model))
> {
>-    model.addClient(*this);
>+    m_playbackSessionModel->addClient(m_weakPtrFactory.createWeakPtr(*this));
>     [m_playerController setPlaybackSessionInterface:this];
>-    [m_playerController setDelegate:&model];
> 
>-    durationChanged(model.duration());
>-    currentTimeChanged(model.currentTime(), [[NSProcessInfo processInfo] systemUptime]);
>-    bufferedTimeChanged(model.bufferedTime());
>-    rateChanged(model.isPlaying(), model.playbackRate());
>-    seekableRangesChanged(model.seekableRanges(), model.seekableTimeRangesLastModifiedTime(), model.liveUpdateInterval());
>-    canPlayFastReverseChanged(model.canPlayFastReverse());
>-    audioMediaSelectionOptionsChanged(model.audioMediaSelectionOptions(), model.audioMediaSelectedIndex());
>-    legibleMediaSelectionOptionsChanged(model.legibleMediaSelectionOptions(), model.legibleMediaSelectedIndex());
>-    externalPlaybackChanged(model.externalPlaybackEnabled(), model.externalPlaybackTargetType(), model.externalPlaybackLocalizedDeviceName());
>-    wirelessVideoPlaybackDisabledChanged(model.wirelessVideoPlaybackDisabled());
>+    durationChanged(m_playbackSessionModel->duration());
>+    currentTimeChanged(m_playbackSessionModel->currentTime(), [[NSProcessInfo processInfo] systemUptime]);
>+    bufferedTimeChanged(m_playbackSessionModel->bufferedTime());
>+    rateChanged(m_playbackSessionModel->isPlaying(), m_playbackSessionModel->playbackRate());
>+    seekableRangesChanged(m_playbackSessionModel->seekableRanges(), m_playbackSessionModel->seekableTimeRangesLastModifiedTime(), m_playbackSessionModel->liveUpdateInterval());
>+    canPlayFastReverseChanged(m_playbackSessionModel->canPlayFastReverse());
>+    audioMediaSelectionOptionsChanged(m_playbackSessionModel->audioMediaSelectionOptions(), m_playbackSessionModel->audioMediaSelectedIndex());
>+    legibleMediaSelectionOptionsChanged(m_playbackSessionModel->legibleMediaSelectionOptions(), m_playbackSessionModel->legibleMediaSelectedIndex());
>+    externalPlaybackChanged(m_playbackSessionModel->externalPlaybackEnabled(), m_playbackSessionModel->externalPlaybackTargetType(), m_playbackSessionModel->externalPlaybackLocalizedDeviceName());
>+    wirelessVideoPlaybackDisabledChanged(m_playbackSessionModel->wirelessVideoPlaybackDisabled());
> }
> 
> PlaybackSessionInterfaceAVKit::~PlaybackSessionInterfaceAVKit()
> {
>+    m_playbackSessionModel->removeClient(*this);
>     [m_playerController setPlaybackSessionInterface:nullptr];
>     [m_playerController setExternalPlaybackActive:false];
>-
>-    invalidate();
> }
> 
> void PlaybackSessionInterfaceAVKit::resetMediaState()
>@@ -206,16 +204,6 @@ void PlaybackSessionInterfaceAVKit::volumeChanged(double volume)
>     [m_playerController volumeChanged:volume];
> }
> 
>-void PlaybackSessionInterfaceAVKit::invalidate()
>-{
>-    if (!m_playbackSessionModel)
>-        return;
>-
>-    [m_playerController setDelegate:nullptr];
>-    m_playbackSessionModel->removeClient(*this);
>-    m_playbackSessionModel = nullptr;
>-}
>-
> }
> 
> #endif // HAVE(AVKIT)
>diff --git a/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.h b/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.h
>index c6d2ead9542cf843420ce953cd3f24f9272bdec6..8ee2a9586baf2b1f938a70571539f5897cd29447 100644
>--- a/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.h
>+++ b/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.h
>@@ -40,6 +40,7 @@
> #include <wtf/RefPtr.h>
> #include <wtf/RetainPtr.h>
> #include <wtf/RunLoop.h>
>+#include <wtf/WeakPtr.h>
> 
> OBJC_CLASS UIViewController;
> OBJC_CLASS UIWindow;
>@@ -64,12 +65,11 @@ class VideoFullscreenInterfaceAVKit final
>     , public ThreadSafeRefCounted<VideoFullscreenInterfaceAVKit> {
> 
> public:
>-    WEBCORE_EXPORT static Ref<VideoFullscreenInterfaceAVKit> create(PlaybackSessionInterfaceAVKit&);
>+    WEBCORE_EXPORT static Ref<VideoFullscreenInterfaceAVKit> create(Ref<PlaybackSessionInterfaceAVKit>&&, Ref<VideoFullscreenModel>&&);
>     virtual ~VideoFullscreenInterfaceAVKit();
>-    WEBCORE_EXPORT void setVideoFullscreenModel(VideoFullscreenModel*);
>-    WEBCORE_EXPORT void setVideoFullscreenChangeObserver(VideoFullscreenChangeObserver*);
>+    WEBCORE_EXPORT void setVideoFullscreenChangeObserver(WeakPtr<VideoFullscreenChangeObserver>);
>     PlaybackSessionInterfaceAVKit& playbackSessionInterface() const { return m_playbackSessionInterface.get(); }
>-    PlaybackSessionModel* playbackSessionModel() const { return m_playbackSessionInterface->playbackSessionModel(); }
>+    PlaybackSessionModel& playbackSessionModel() const { return m_playbackSessionInterface->playbackSessionModel(); }
> 
>     // VideoFullscreenModelClient
>     WEBCORE_EXPORT void hasVideoChanged(bool) final;
>@@ -82,7 +82,6 @@ public:
>     WEBCORE_EXPORT void enterFullscreen();
>     WEBCORE_EXPORT void exitFullscreen(const IntRect& finalRect);
>     WEBCORE_EXPORT void cleanupFullscreen();
>-    WEBCORE_EXPORT void invalidate();
>     WEBCORE_EXPORT void requestHideAndExitFullscreen();
>     WEBCORE_EXPORT void preparedToReturnToInline(bool visible, const IntRect& inlineRect);
>     WEBCORE_EXPORT void preparedToExitFullscreen();
>@@ -131,7 +130,7 @@ public:
>     Mode m_targetMode;
> #endif
> 
>-    VideoFullscreenModel* videoFullscreenModel() const { return m_videoFullscreenModel; }
>+    VideoFullscreenModel& videoFullscreenModel() const { return m_videoFullscreenModel; }
>     bool shouldExitFullscreenWithReason(ExitFullScreenReason);
>     HTMLMediaElementEnums::VideoFullscreenMode mode() const { return m_currentMode.mode(); }
>     bool allowsPictureInPicturePlayback() const { return m_allowsPictureInPicturePlayback; }
>@@ -164,7 +163,7 @@ public:
> #endif
> 
> protected:
>-    WEBCORE_EXPORT VideoFullscreenInterfaceAVKit(PlaybackSessionInterfaceAVKit&);
>+    WEBCORE_EXPORT VideoFullscreenInterfaceAVKit(Ref<PlaybackSessionInterfaceAVKit>&&, Ref<VideoFullscreenModel>&&);
> 
> #if ENABLE(FULLSCREEN_API)
>     void doSetup();
>@@ -180,10 +179,10 @@ protected:
>     WebAVPlayerController *playerController() const;
> 
>     Ref<PlaybackSessionInterfaceAVKit> m_playbackSessionInterface;
>+    Ref<VideoFullscreenModel> m_videoFullscreenModel;
>     RetainPtr<WebAVPlayerViewControllerDelegate> m_playerViewControllerDelegate;
>     RetainPtr<WebAVPlayerViewController> m_playerViewController;
>-    VideoFullscreenModel* m_videoFullscreenModel { nullptr };
>-    VideoFullscreenChangeObserver* m_fullscreenChangeObserver { nullptr };
>+    WeakPtr<VideoFullscreenChangeObserver> m_fullscreenChangeObserver;
> 
>     // These are only used when fullscreen is presented in a separate window.
>     RetainPtr<UIWindow> m_window;
>diff --git a/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.mm b/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.mm
>index 5cc320e19dad39c009c73368a5871c86093e8b7d..73244eec2eb51f208f6d36e196c413161a85cf2c 100644
>--- a/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.mm
>+++ b/Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.mm
>@@ -289,8 +289,7 @@ - (void)layoutSublayers
>     } else if ([getAVLayerVideoGravityResizeAspectFill() isEqualToString:self.videoGravity]) {
>         sourceVideoFrame = smallestRectWithAspectRatioAroundRect(videoAspectRatio, self.modelVideoLayerFrame);
>         self.modelVideoLayerFrame = CGRectMake(0, 0, sourceVideoFrame.width(), sourceVideoFrame.height());
>-        if (auto* model = _fullscreenInterface->videoFullscreenModel())
>-            model->setVideoLayerFrame(self.modelVideoLayerFrame);
>+        _fullscreenInterface->videoFullscreenModel().setVideoLayerFrame(self.modelVideoLayerFrame);
>         targetVideoFrame = smallestRectWithAspectRatioAroundRect(videoAspectRatio, self.bounds);
>     } else
>         ASSERT_NOT_REACHED();
>@@ -325,8 +324,7 @@ - (void)resolveBounds
>     
>     if (!CGRectEqualToRect(self.modelVideoLayerFrame, [self bounds])) {
>         self.modelVideoLayerFrame = [self bounds];
>-        if (auto* model = _fullscreenInterface->videoFullscreenModel())
>-            model->setVideoLayerFrame(self.modelVideoLayerFrame);
>+        _fullscreenInterface->videoFullscreenModel().setVideoLayerFrame(self.modelVideoLayerFrame);
>     }
>     [(UIView *)[_videoSublayer delegate] setTransform:CGAffineTransformIdentity];
>     
>@@ -350,8 +348,7 @@ - (void)setVideoGravity:(NSString *)videoGravity
>     else
>         ASSERT_NOT_REACHED();
>     
>-    if (auto* model = _fullscreenInterface->videoFullscreenModel())
>-        model->setVideoLayerGravity(gravity);
>+    _fullscreenInterface->videoFullscreenModel().setVideoLayerGravity(gravity);
> }
> 
> - (NSString *)videoGravity
>@@ -725,15 +722,16 @@ - (void)removeFromParentViewController
> }
> @end
> 
>-Ref<VideoFullscreenInterfaceAVKit> VideoFullscreenInterfaceAVKit::create(PlaybackSessionInterfaceAVKit& playbackSessionInterface)
>+Ref<VideoFullscreenInterfaceAVKit> VideoFullscreenInterfaceAVKit::create(Ref<PlaybackSessionInterfaceAVKit>&& playbackSessionInterface, Ref<VideoFullscreenModel>&& videoFullscreenModel)
> {
>-    Ref<VideoFullscreenInterfaceAVKit> interface = adoptRef(*new VideoFullscreenInterfaceAVKit(playbackSessionInterface));
>+    Ref<VideoFullscreenInterfaceAVKit> interface = adoptRef(*new VideoFullscreenInterfaceAVKit(WTFMove(playbackSessionInterface), WTFMove(videoFullscreenModel)));
>     [interface->m_playerViewControllerDelegate setFullscreenInterface:interface.ptr()];
>     return interface;
> }
> 
>-VideoFullscreenInterfaceAVKit::VideoFullscreenInterfaceAVKit(PlaybackSessionInterfaceAVKit& playbackSessionInterface)
>-    : m_playbackSessionInterface(playbackSessionInterface)
>+VideoFullscreenInterfaceAVKit::VideoFullscreenInterfaceAVKit(Ref<PlaybackSessionInterfaceAVKit>&& playbackSessionInterface, Ref<VideoFullscreenModel>&& videoFullscreenModel)
>+    : m_playbackSessionInterface(WTFMove(playbackSessionInterface))
>+    , m_videoFullscreenModel(WTFMove(videoFullscreenModel))
>     , m_playerViewControllerDelegate(adoptNS([[WebAVPlayerViewControllerDelegate alloc] init]))
>     , m_watchdogTimer(RunLoop::main(), this, &VideoFullscreenInterfaceAVKit::watchdogTimerFired)
> {
>@@ -744,8 +742,7 @@ VideoFullscreenInterfaceAVKit::~VideoFullscreenInterfaceAVKit()
>     WebAVPlayerController* playerController = this->playerController();
>     if (playerController && playerController.externalPlaybackActive)
>         externalPlaybackChanged(false, PlaybackSessionModel::TargetTypeNone, "");
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->removeClient(*this);
>+    videoFullscreenModel().removeClient(*this);
> }
> 
> WebAVPlayerController *VideoFullscreenInterfaceAVKit::playerController() const
>@@ -753,21 +750,7 @@ WebAVPlayerController *VideoFullscreenInterfaceAVKit::playerController() const
>     return m_playbackSessionInterface->playerController();
> }
> 
>-void VideoFullscreenInterfaceAVKit::setVideoFullscreenModel(VideoFullscreenModel* model)
>-{
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->removeClient(*this);
>-
>-    m_videoFullscreenModel = model;
>-
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->addClient(*this);
>-
>-    hasVideoChanged(m_videoFullscreenModel ? m_videoFullscreenModel->hasVideo() : false);
>-    videoDimensionsChanged(m_videoFullscreenModel ? m_videoFullscreenModel->videoDimensions() : FloatSize());
>-}
>-
>-void VideoFullscreenInterfaceAVKit::setVideoFullscreenChangeObserver(VideoFullscreenChangeObserver* observer)
>+void VideoFullscreenInterfaceAVKit::setVideoFullscreenChangeObserver(WeakPtr<VideoFullscreenChangeObserver> observer)
> {
>     m_fullscreenChangeObserver = observer;
> }
>@@ -807,7 +790,7 @@ bool VideoFullscreenInterfaceAVKit::pictureInPictureWasStartedWhenEnteringBackgr
> void VideoFullscreenInterfaceAVKit::applicationDidBecomeActive()
> {
>     LOG(Fullscreen, "VideoFullscreenInterfaceAVKit::applicationDidBecomeActive(%p)", this);
>-    if (m_shouldReturnToFullscreenAfterEnteringForeground && m_videoFullscreenModel && m_videoFullscreenModel->isVisible()) {
>+    if (m_shouldReturnToFullscreenAfterEnteringForeground && videoFullscreenModel().isVisible()) {
>         [m_playerViewController stopPictureInPicture];
>         return;
>     }
>@@ -884,7 +867,7 @@ void VideoFullscreenInterfaceAVKit::setupFullscreen(UIView& videoView, const Int
>     [playerController() setPictureInPicturePossible:m_allowsPictureInPicturePlayback];
> 
> #if PLATFORM(WATCHOS)
>-    m_viewController = videoFullscreenModel()->createVideoFullscreenViewController(m_playerViewController.get().avPlayerViewController);
>+    m_viewController = videoFullscreenModel().createVideoFullscreenViewController(m_playerViewController.get().avPlayerViewController);
> #endif
> 
>     if (m_viewController) {
>@@ -949,7 +932,7 @@ static UIViewController *fallbackViewController(UIView *view)
> 
> UIViewController *VideoFullscreenInterfaceAVKit::presentingViewController()
> {
>-    auto *controller = videoFullscreenModel()->presentingViewController();
>+    auto *controller = videoFullscreenModel().presentingViewController();
>     if (!controller)
>         controller = fallbackViewController(m_parentView.get());
> 
>@@ -1077,14 +1060,6 @@ void VideoFullscreenInterfaceAVKit::cleanupFullscreen()
>     m_enterRequested = false;
> }
> 
>-void VideoFullscreenInterfaceAVKit::invalidate()
>-{
>-    m_videoFullscreenModel = nil;
>-    m_fullscreenChangeObserver = nil;
>-    
>-    cleanupFullscreen();
>-}
>-
> void VideoFullscreenInterfaceAVKit::requestHideAndExitFullscreen()
> {
>     if (!m_enterRequested)
>@@ -1098,9 +1073,9 @@ void VideoFullscreenInterfaceAVKit::requestHideAndExitFullscreen()
>     [m_window setHidden:YES];
>     [[m_playerViewController view] setHidden:YES];
> 
>-    if (playbackSessionModel() && m_videoFullscreenModel && !m_exitRequested) {
>-        playbackSessionModel()->pause();
>-        m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>+    if (!m_exitRequested) {
>+        playbackSessionModel().pause();
>+        videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>     }
> }
> 
>@@ -1120,7 +1095,7 @@ void VideoFullscreenInterfaceAVKit::preparedToExitFullscreen()
>         return;
> 
>     m_waitingForPreparedToExit = false;
>-    m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone, true);
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone, true);
> }
> 
> bool VideoFullscreenInterfaceAVKit::mayAutomaticallyShowVideoPictureInPicture() const
>@@ -1139,8 +1114,7 @@ void VideoFullscreenInterfaceAVKit::willStartPictureInPicture()
> {
>     LOG(Fullscreen, "VideoFullscreenInterfaceAVKit::willStartPictureInPicture(%p)", this);
>     setMode(HTMLMediaElementEnums::VideoFullscreenModePictureInPicture);
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->willEnterPictureInPicture();
>+    videoFullscreenModel().willEnterPictureInPicture();
> }
> 
> void VideoFullscreenInterfaceAVKit::didStartPictureInPicture()
>@@ -1166,8 +1140,7 @@ void VideoFullscreenInterfaceAVKit::didStartPictureInPicture()
> 
>     if (m_fullscreenChangeObserver)
>         m_fullscreenChangeObserver->didEnterFullscreen();
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->didEnterPictureInPicture();
>+    videoFullscreenModel().didEnterPictureInPicture();
> }
> 
> void VideoFullscreenInterfaceAVKit::failedToStartPictureInPicture()
>@@ -1182,11 +1155,8 @@ void VideoFullscreenInterfaceAVKit::failedToStartPictureInPicture()
> 
>     if (m_fullscreenChangeObserver)
>         m_fullscreenChangeObserver->didEnterFullscreen();
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->failedToEnterPictureInPicture();
>-
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>+    videoFullscreenModel().failedToEnterPictureInPicture();
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
> }
> 
> void VideoFullscreenInterfaceAVKit::willStopPictureInPicture()
>@@ -1202,10 +1172,8 @@ void VideoFullscreenInterfaceAVKit::willStopPictureInPicture()
>     [m_window setHidden:NO];
>     [[m_playerViewController view] setHidden:NO];
> 
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->willExitPictureInPicture();
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>+    videoFullscreenModel().willExitPictureInPicture();
> }
> 
> void VideoFullscreenInterfaceAVKit::didStopPictureInPicture()
>@@ -1228,8 +1196,7 @@ void VideoFullscreenInterfaceAVKit::didStopPictureInPicture()
> 
>     if (m_fullscreenChangeObserver)
>         m_fullscreenChangeObserver->didExitFullscreen();
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->didExitPictureInPicture();
>+    videoFullscreenModel().didExitPictureInPicture();
> }
> 
> void VideoFullscreenInterfaceAVKit::prepareForPictureInPictureStopWithCompletionHandler(void (^completionHandler)(BOOL restored))
>@@ -1266,9 +1233,6 @@ void VideoFullscreenInterfaceAVKit::prepareForPictureInPictureStopWithCompletion
> 
> bool VideoFullscreenInterfaceAVKit::shouldExitFullscreenWithReason(VideoFullscreenInterfaceAVKit::ExitFullScreenReason reason)
> {
>-    if (!m_videoFullscreenModel)
>-        return true;
>-
>     if (reason == ExitFullScreenReason::PictureInPictureStarted) {
>         if (pictureInPictureWasStartedWhenEnteringBackground())
>             return false;
>@@ -1278,8 +1242,8 @@ bool VideoFullscreenInterfaceAVKit::shouldExitFullscreenWithReason(VideoFullscre
>         return true;
>     }
> 
>-    if (playbackSessionModel() && (reason == ExitFullScreenReason::DoneButtonTapped || reason == ExitFullScreenReason::RemoteControlStopEventReceived))
>-        playbackSessionModel()->pause();
>+    if (reason == ExitFullScreenReason::DoneButtonTapped || reason == ExitFullScreenReason::RemoteControlStopEventReceived)
>+        playbackSessionModel().pause();
> 
>     if (!m_watchdogTimer.isActive() && !ignoreWatchdogForDebugging)
>         m_watchdogTimer.startOneShot(defaultWatchdogTimerInterval);
>@@ -1293,7 +1257,7 @@ bool VideoFullscreenInterfaceAVKit::shouldExitFullscreenWithReason(VideoFullscre
> #endif
> 
>     BOOL finished = reason == ExitFullScreenReason::DoneButtonTapped || reason == ExitFullScreenReason::PinchGestureHandled;
>-    m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone, finished);
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone, finished);
> 
>     return false;
> }
>@@ -1385,14 +1349,6 @@ void VideoFullscreenInterfaceAVKit::cleanupFullscreen()
>         m_fullscreenChangeObserver->didCleanupFullscreen();
> }
> 
>-void VideoFullscreenInterfaceAVKit::invalidate()
>-{
>-    m_videoFullscreenModel = nil;
>-    m_fullscreenChangeObserver = nil;
>-    
>-    cleanupFullscreen();
>-}
>-
> void VideoFullscreenInterfaceAVKit::requestHideAndExitFullscreen()
> {
>     if (m_currentMode.hasPictureInPicture())
>@@ -1403,10 +1359,8 @@ void VideoFullscreenInterfaceAVKit::requestHideAndExitFullscreen()
>     [m_window setHidden:YES];
>     [[m_playerViewController view] setHidden:YES];
> 
>-    if (playbackSessionModel() && m_videoFullscreenModel) {
>-        playbackSessionModel()->pause();
>-        m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>-    }
>+    playbackSessionModel().pause();
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
> }
> 
> void VideoFullscreenInterfaceAVKit::preparedToReturnToInline(bool visible, const IntRect& inlineRect)
>@@ -1445,8 +1399,7 @@ void VideoFullscreenInterfaceAVKit::willStartPictureInPicture()
> 
>     if (!m_hasVideoContentLayer)
>         m_fullscreenChangeObserver->requestVideoContentLayer();
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->willEnterPictureInPicture();
>+    videoFullscreenModel().willEnterPictureInPicture();
> }
> 
> void VideoFullscreenInterfaceAVKit::didStartPictureInPicture()
>@@ -1466,8 +1419,7 @@ void VideoFullscreenInterfaceAVKit::didStartPictureInPicture()
>         [[m_playerViewController view] setHidden:YES];
>     }
> 
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->didEnterPictureInPicture();
>+    videoFullscreenModel().didEnterPictureInPicture();
> 
>     if (m_enterFullscreenNeedsEnterPictureInPicture)
>         doEnterFullscreen();
>@@ -1485,11 +1437,8 @@ void VideoFullscreenInterfaceAVKit::failedToStartPictureInPicture()
>     if (m_fullscreenChangeObserver)
>         m_fullscreenChangeObserver->didEnterFullscreen();
> 
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->failedToEnterPictureInPicture();
>-
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>+    videoFullscreenModel().failedToEnterPictureInPicture();
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
> }
> 
> void VideoFullscreenInterfaceAVKit::willStopPictureInPicture()
>@@ -1504,8 +1453,7 @@ void VideoFullscreenInterfaceAVKit::willStopPictureInPicture()
>     [m_window setHidden:NO];
>     [[m_playerViewController view] setHidden:NO];
> 
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->willExitPictureInPicture();
>+    videoFullscreenModel().willExitPictureInPicture();
> }
> 
> void VideoFullscreenInterfaceAVKit::didStopPictureInPicture()
>@@ -1525,13 +1473,11 @@ void VideoFullscreenInterfaceAVKit::didStopPictureInPicture()
>     [m_playerLayerView setBackgroundColor:clearUIColor()];
>     [[m_playerViewController view] setBackgroundColor:clearUIColor()];
> 
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
> 
>     clearMode(HTMLMediaElementEnums::VideoFullscreenModePictureInPicture);
> 
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->didExitPictureInPicture();
>+    videoFullscreenModel().didExitPictureInPicture();
> 
>     if (m_enterFullscreenNeedsExitPictureInPicture)
>         doEnterFullscreen();
>@@ -1567,17 +1513,14 @@ void VideoFullscreenInterfaceAVKit::prepareForPictureInPictureStopWithCompletion
> 
> bool VideoFullscreenInterfaceAVKit::shouldExitFullscreenWithReason(VideoFullscreenInterfaceAVKit::ExitFullScreenReason reason)
> {
>-    if (!m_videoFullscreenModel)
>-        return true;
>-
>     if (reason == ExitFullScreenReason::PictureInPictureStarted)
>         return false;
> 
>-    if (playbackSessionModel() && (reason == ExitFullScreenReason::DoneButtonTapped || reason == ExitFullScreenReason::RemoteControlStopEventReceived))
>-        playbackSessionModel()->pause();
>+    if (reason == ExitFullScreenReason::DoneButtonTapped || reason == ExitFullScreenReason::RemoteControlStopEventReceived)
>+        playbackSessionModel().pause();
> 
>     BOOL finished = reason == ExitFullScreenReason::DoneButtonTapped || reason == ExitFullScreenReason::PinchGestureHandled;
>-    m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone, finished);
>+    videoFullscreenModel().requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone, finished);
> 
>     if (!m_watchdogTimer.isActive() && !ignoreWatchdogForDebugging)
>         m_watchdogTimer.startOneShot(defaultWatchdogTimerInterval);
>@@ -1672,8 +1615,7 @@ void VideoFullscreenInterfaceAVKit::doSetup()
>     [playerLayer setModelVideoLayerFrame:modelVideoLayerFrame];
>     [playerLayer setVideoDimensions:[playerController() contentDimensions]];
>     playerLayer.fullscreenInterface = this;
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->setVideoLayerFrame(modelVideoLayerFrame);
>+    videoFullscreenModel().setVideoLayerFrame(modelVideoLayerFrame);
> 
>     if (!m_playerViewController)
>         m_playerViewController = adoptNS([[WebAVPlayerViewController alloc] initWithFullscreenInterface:this]);
>@@ -1685,7 +1627,7 @@ void VideoFullscreenInterfaceAVKit::doSetup()
>     [playerController() setPictureInPicturePossible:m_allowsPictureInPicturePlayback];
> 
> #if PLATFORM(WATCHOS)
>-    m_viewController = videoFullscreenModel()->createVideoFullscreenViewController(m_playerViewController.get().avPlayerViewController);
>+    m_viewController = videoFullscreenModel().createVideoFullscreenViewController(m_playerViewController.get().avPlayerViewController);
> #endif
> 
>     if (m_viewController) {
>@@ -1892,8 +1834,7 @@ void VideoFullscreenInterfaceAVKit::setMode(HTMLMediaElementEnums::VideoFullscre
>         return;
> 
>     m_currentMode.setMode(mode);
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->fullscreenModeChanged(m_currentMode.mode());
>+    videoFullscreenModel().fullscreenModeChanged(m_currentMode.mode());
> }
> 
> void VideoFullscreenInterfaceAVKit::clearMode(HTMLMediaElementEnums::VideoFullscreenMode mode)
>@@ -1902,8 +1843,7 @@ void VideoFullscreenInterfaceAVKit::clearMode(HTMLMediaElementEnums::VideoFullsc
>         return;
> 
>     m_currentMode.clearMode(mode);
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->fullscreenModeChanged(m_currentMode.mode());
>+    videoFullscreenModel().fullscreenModeChanged(m_currentMode.mode());
> }
> 
> bool VideoFullscreenInterfaceAVKit::isPlayingVideoInEnhancedFullscreen() const
>diff --git a/Source/WebCore/platform/ios/WebAVPlayerController.h b/Source/WebCore/platform/ios/WebAVPlayerController.h
>index a45346cddc0f475a91a3897b5aa263b7f81c7225..1e78ab06fe4b47b13d6030501a453412d2c26862 100644
>--- a/Source/WebCore/platform/ios/WebAVPlayerController.h
>+++ b/Source/WebCore/platform/ios/WebAVPlayerController.h
>@@ -26,6 +26,7 @@
> #if PLATFORM(IOS) && HAVE(AVKIT)
> 
> #import <pal/spi/cocoa/AVKitSPI.h>
>+#import <wtf/WeakPtr.h>
> 
> namespace WebCore {
> class PlaybackSessionModel;
>@@ -39,13 +40,14 @@ class PlaybackSessionInterfaceAVKit;
> @interface WebAVPlayerController : NSObject {
>     WebAVMediaSelectionOption *_currentAudioMediaSelectionOption;
>     WebAVMediaSelectionOption *_currentLegibleMediaSelectionOption;
>+    RefPtr<WebCore::PlaybackSessionInterfaceAVKit> _playbackSessionInterface;
>     BOOL _pictureInPictureInterrupted;
>     BOOL _muted;
> }
> 
> @property (retain) AVPlayerController* playerControllerProxy;
>-@property (assign) WebCore::PlaybackSessionModel* delegate;
>-@property (assign) WebCore::PlaybackSessionInterfaceAVKit* playbackSessionInterface;
>+@property (readonly) WebCore::PlaybackSessionModel* delegate;
>+@property WebCore::PlaybackSessionInterfaceAVKit* playbackSessionInterface;
> 
> @property (readonly) BOOL canScanForward;
> @property BOOL canScanBackward;
>diff --git a/Source/WebCore/platform/ios/WebAVPlayerController.mm b/Source/WebCore/platform/ios/WebAVPlayerController.mm
>index 84814233e8d4f84e3da5374574fb1ad53e7e94bd..66e20319a1cf39038cf15d8ba4f21e0897d2308d 100644
>--- a/Source/WebCore/platform/ios/WebAVPlayerController.mm
>+++ b/Source/WebCore/platform/ios/WebAVPlayerController.mm
>@@ -95,6 +95,23 @@ - (void)dealloc
>     [super dealloc];
> }
> 
>+@dynamic delegate;
>+- (WebCore::PlaybackSessionModel*)delegate
>+{
>+    return _playbackSessionInterface ? &_playbackSessionInterface->playbackSessionModel() : nullptr;
>+}
>+
>+@dynamic playbackSessionInterface;
>+- (WebCore::PlaybackSessionInterfaceAVKit*)playbackSessionInterface
>+{
>+    return _playbackSessionInterface.get();
>+}
>+
>+- (void)setPlaybackSessionInterface:(WebCore::PlaybackSessionInterfaceAVKit*)playbackSessionInterface
>+{
>+    _playbackSessionInterface = playbackSessionInterface;
>+}
>+
> - (AVPlayer *)player
> {
>     return nil;
>diff --git a/Source/WebCore/platform/ios/WebVideoFullscreenControllerAVKit.mm b/Source/WebCore/platform/ios/WebVideoFullscreenControllerAVKit.mm
>index 7ff0cf574d6fd4bf57eb52cfc92c0f44e9c204c7..12dfa8e6de8c49692e10064e1c3243ef1016af35 100644
>--- a/Source/WebCore/platform/ios/WebVideoFullscreenControllerAVKit.mm
>+++ b/Source/WebCore/platform/ios/WebVideoFullscreenControllerAVKit.mm
>@@ -99,11 +99,11 @@ -(void)didFinishFullscreen:(VideoFullscreenControllerContext*)context;
> @end
> 
> class VideoFullscreenControllerContext final
>-    : private VideoFullscreenModel
>-    , private VideoFullscreenModelClient
>-    , private VideoFullscreenChangeObserver
>+    : public VideoFullscreenModel
>+    , public VideoFullscreenModelClient
>+    , public VideoFullscreenChangeObserver
>     , private PlaybackSessionModel
>-    , private PlaybackSessionModelClient
>+    , public PlaybackSessionModelClient
>     , public ThreadSafeRefCounted<VideoFullscreenControllerContext> {
> 
> public:
>@@ -118,6 +118,9 @@ public:
>     void requestHideAndExitFullscreen();
>     void invalidate();
> 
>+    using ThreadSafeRefCounted::ref;
>+    using ThreadSafeRefCounted::deref;
>+
> private:
>     VideoFullscreenControllerContext() { }
> 
>@@ -137,7 +140,9 @@ private:
>     void videoDimensionsChanged(const FloatSize&) override;
> 
>     // PlaybackSessionModel
>-    void addClient(PlaybackSessionModelClient&) override;
>+    void refPlaybackSessionModel() final { ref(); }
>+    void derefPlaybackSessionModel() final { deref(); }
>+    void addClient(WeakPtr<PlaybackSessionModelClient>&&) override;
>     void removeClient(PlaybackSessionModelClient&) override;
>     void play() override;
>     void pause() override;
>@@ -190,7 +195,9 @@ private:
>     void volumeChanged(double) override;
> 
>     // VideoFullscreenModel
>-    void addClient(VideoFullscreenModelClient&) override;
>+    void refVideoFullscreenModel() final { ref(); }
>+    void derefVideoFullscreenModel() final { deref(); }
>+    void addClient(WeakPtr<VideoFullscreenModelClient>&&) override;
>     void removeClient(VideoFullscreenModelClient&) override;
>     void requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenMode, bool finishedWithMedia = false) override;
>     void setVideoLayerFrame(FloatRect) override;
>@@ -208,14 +215,17 @@ private:
>     void willExitPictureInPicture() final;
>     void didExitPictureInPicture() final;
> 
>-    HashSet<PlaybackSessionModelClient*> m_playbackClients;
>-    HashSet<VideoFullscreenModelClient*> m_fullscreenClients;
>+    Vector<WeakPtr<PlaybackSessionModelClient>> m_playbackClients;
>+    Vector<WeakPtr<VideoFullscreenModelClient>> m_fullscreenClients;
>     RefPtr<VideoFullscreenInterfaceAVKit> m_interface;
>     RefPtr<VideoFullscreenModelVideoElement> m_fullscreenModel;
>     RefPtr<PlaybackSessionModelMediaElement> m_playbackModel;
>     RefPtr<HTMLVideoElement> m_videoElement;
>     RetainPtr<UIView> m_videoFullscreenView;
>     RetainPtr<WebVideoFullscreenController> m_controller;
>+    WeakPtrFactory<PlaybackSessionModelClient> m_playbackClientFactory;
>+    WeakPtrFactory<VideoFullscreenModelClient> m_fullscreenModelClientFactory;
>+    WeakPtrFactory<VideoFullscreenChangeObserver> m_fullscreenChangeObserverFactory;
> };
> 
> #pragma mark VideoFullscreenChangeObserver
>@@ -319,8 +329,6 @@ void VideoFullscreenControllerContext::didExitFullscreen()
> void VideoFullscreenControllerContext::didCleanupFullscreen()
> {
>     ASSERT(isUIThread());
>-    m_interface->setVideoFullscreenModel(nullptr);
>-    m_interface->setVideoFullscreenChangeObserver(nullptr);
>     m_interface = nullptr;
>     m_videoFullscreenView = nil;
> 
>@@ -329,6 +337,7 @@ void VideoFullscreenControllerContext::didCleanupFullscreen()
>         m_fullscreenModel->setVideoElement(nullptr);
>         m_playbackModel->setMediaElement(nullptr);
>         m_playbackModel->removeClient(*this);
>+        m_playbackModel = nullptr;
>         m_fullscreenModel->removeClient(*this);
>         m_fullscreenModel = nullptr;
>         m_videoElement = nullptr;
>@@ -543,16 +552,16 @@ void VideoFullscreenControllerContext::volumeChanged(double volume)
> }
> #pragma mark VideoFullscreenModel
> 
>-void VideoFullscreenControllerContext::addClient(VideoFullscreenModelClient& client)
>+void VideoFullscreenControllerContext::addClient(WeakPtr<VideoFullscreenModelClient>&& client)
> {
>-    ASSERT(!m_fullscreenClients.contains(&client));
>-    m_fullscreenClients.add(&client);
>+    ASSERT(!m_fullscreenClients.contains(client));
>+    m_fullscreenClients.append(WTFMove(client));
> }
> 
> void VideoFullscreenControllerContext::removeClient(VideoFullscreenModelClient& client)
> {
>     ASSERT(m_fullscreenClients.contains(&client));
>-    m_fullscreenClients.remove(&client);
>+    m_fullscreenClients.removeAll(&client);
> }
> 
> void VideoFullscreenControllerContext::requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenMode mode, bool finishedWithMedia)
>@@ -636,35 +645,35 @@ bool VideoFullscreenControllerContext::isPictureInPictureActive() const
> void VideoFullscreenControllerContext::willEnterPictureInPicture()
> {
>     ASSERT(isUIThread());
>-    for (auto* client : m_fullscreenClients)
>+    for (auto& client : m_fullscreenClients)
>         client->willEnterPictureInPicture();
> }
> 
> void VideoFullscreenControllerContext::didEnterPictureInPicture()
> {
>     ASSERT(isUIThread());
>-    for (auto* client : m_fullscreenClients)
>+    for (auto& client : m_fullscreenClients)
>         client->didEnterPictureInPicture();
> }
> 
> void VideoFullscreenControllerContext::failedToEnterPictureInPicture()
> {
>     ASSERT(isUIThread());
>-    for (auto* client : m_fullscreenClients)
>+    for (auto& client : m_fullscreenClients)
>         client->failedToEnterPictureInPicture();
> }
> 
> void VideoFullscreenControllerContext::willExitPictureInPicture()
> {
>     ASSERT(isUIThread());
>-    for (auto* client : m_fullscreenClients)
>+    for (auto& client : m_fullscreenClients)
>         client->willExitPictureInPicture();
> }
> 
> void VideoFullscreenControllerContext::didExitPictureInPicture()
> {
>     ASSERT(isUIThread());
>-    for (auto* client : m_fullscreenClients)
>+    for (auto& client : m_fullscreenClients)
>         client->didExitPictureInPicture();
> }
> 
>@@ -676,16 +685,16 @@ FloatSize VideoFullscreenControllerContext::videoDimensions() const
> 
> #pragma mark - PlaybackSessionModel
> 
>-void VideoFullscreenControllerContext::addClient(PlaybackSessionModelClient& client)
>+void VideoFullscreenControllerContext::addClient(WeakPtr<PlaybackSessionModelClient>&& client)
> {
>-    ASSERT(!m_playbackClients.contains(&client));
>-    m_playbackClients.add(&client);
>+    ASSERT(!m_playbackClients.contains(client));
>+    m_playbackClients.append(WTFMove(client));
> }
> 
> void VideoFullscreenControllerContext::removeClient(PlaybackSessionModelClient& client)
> {
>     ASSERT(m_playbackClients.contains(&client));
>-    m_playbackClients.remove(&client);
>+    m_playbackClients.removeAll(&client);
> }
> 
> void VideoFullscreenControllerContext::play()
>@@ -937,11 +946,11 @@ void VideoFullscreenControllerContext::setUpFullscreen(HTMLVideoElement& videoEl
>     RetainPtr<UIView> viewRef = view;
>     m_videoElement = &videoElement;
>     m_playbackModel = PlaybackSessionModelMediaElement::create();
>-    m_playbackModel->addClient(*this);
>+    m_playbackModel->addClient(m_playbackClientFactory.createWeakPtr(*this));
>     m_playbackModel->setMediaElement(m_videoElement.get());
> 
>     m_fullscreenModel = VideoFullscreenModelVideoElement::create();
>-    m_fullscreenModel->addClient(*this);
>+    m_fullscreenModel->addClient(m_fullscreenModelClientFactory.createWeakPtr(*this));
>     m_fullscreenModel->setVideoElement(m_videoElement.get());
> 
>     bool allowsPictureInPicture = m_videoElement->webkitSupportsPresentationMode(HTMLVideoElement::VideoPresentationMode::PictureInPicture);
>@@ -954,10 +963,8 @@ void VideoFullscreenControllerContext::setUpFullscreen(HTMLVideoElement& videoEl
>         ASSERT(isUIThread());
> 
>         Ref<PlaybackSessionInterfaceAVKit> sessionInterface = PlaybackSessionInterfaceAVKit::create(*this);
>-        m_interface = VideoFullscreenInterfaceAVKit::create(sessionInterface.get());
>-        m_interface->setVideoFullscreenChangeObserver(this);
>-        m_interface->setVideoFullscreenModel(this);
>-        m_interface->setVideoFullscreenChangeObserver(this);
>+        m_interface = VideoFullscreenInterfaceAVKit::create(sessionInterface.get(), *this);
>+        m_interface->setVideoFullscreenChangeObserver(m_fullscreenChangeObserverFactory.createWeakPtr(*this));
> 
>         m_videoFullscreenView = adoptNS([allocUIViewInstance() init]);
> 
>diff --git a/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.h b/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.h
>index 9aa955fc44fa4c84b9e4a0f66a943aa5b84b29e8..541951f5e2366b52f463d823c21841ad504b178f 100644
>--- a/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.h
>+++ b/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.h
>@@ -45,9 +45,9 @@ class WEBCORE_EXPORT PlaybackSessionInterfaceMac final
>     , public PlaybackSessionModelClient
>     , public RefCounted<PlaybackSessionInterfaceMac> {
> public:
>-    static Ref<PlaybackSessionInterfaceMac> create(PlaybackSessionModel&);
>-    virtual ~PlaybackSessionInterfaceMac();
>-    PlaybackSessionModel* playbackSessionModel() const;
>+    static Ref<PlaybackSessionInterfaceMac> create(Ref<PlaybackSessionModel>&&);
>+    virtual ~PlaybackSessionInterfaceMac() = default;
>+    PlaybackSessionModel& playbackSessionModel() const;
> 
>     // PlaybackSessionInterface
>     void resetMediaState() final;
>@@ -63,7 +63,6 @@ public:
>     void legibleMediaSelectionIndexChanged(uint64_t) final;
>     void externalPlaybackChanged(bool /* enabled */, PlaybackSessionModel::ExternalPlaybackTargetType, const String& /* localizedDeviceName */) final;
> 
>-    void invalidate();
>     void ensureControlsManager();
> #if ENABLE(WEB_PLAYBACK_CONTROLS_MANAGER)
>     void setPlayBackControlsManager(WebPlaybackControlsManager *);
>@@ -73,8 +72,9 @@ public:
>     void endScrubbing();
> 
> private:
>-    PlaybackSessionInterfaceMac(PlaybackSessionModel&);
>-    PlaybackSessionModel* m_playbackSessionModel { nullptr };
>+    PlaybackSessionInterfaceMac(Ref<PlaybackSessionModel>&&);
>+    Ref<PlaybackSessionModel> m_playbackSessionModel;
>+    WeakPtrFactory<PlaybackSessionModelClient> m_weakPtrFactory;
> #if ENABLE(WEB_PLAYBACK_CONTROLS_MANAGER)
>     WebPlaybackControlsManager *m_playbackControlsManager  { nullptr };
> 
>diff --git a/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.mm b/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.mm
>index 602eddba51fce11393dbce445fbb86086648c967..eeafe0074284ef4f55b06ed9a7c43d2372b2ee19 100644
>--- a/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.mm
>+++ b/Source/WebCore/platform/mac/PlaybackSessionInterfaceMac.mm
>@@ -44,24 +44,18 @@ SOFT_LINK_CLASS_OPTIONAL(AVKit, AVValueTiming)
> 
> namespace WebCore {
> 
>-Ref<PlaybackSessionInterfaceMac> PlaybackSessionInterfaceMac::create(PlaybackSessionModel& model)
>+Ref<PlaybackSessionInterfaceMac> PlaybackSessionInterfaceMac::create(Ref<PlaybackSessionModel>&& model)
> {
>-    auto interface = adoptRef(*new PlaybackSessionInterfaceMac(model));
>-    model.addClient(interface);
>-    return interface;
>+    return adoptRef(*new PlaybackSessionInterfaceMac(WTFMove(model)));
> }
> 
>-PlaybackSessionInterfaceMac::PlaybackSessionInterfaceMac(PlaybackSessionModel& model)
>-    : m_playbackSessionModel(&model)
>+PlaybackSessionInterfaceMac::PlaybackSessionInterfaceMac(Ref<PlaybackSessionModel>&& model)
>+    : m_playbackSessionModel(WTFMove(model))
> {
>+    playbackSessionModel().addClient(m_weakPtrFactory.createWeakPtr(*this));
> }
> 
>-PlaybackSessionInterfaceMac::~PlaybackSessionInterfaceMac()
>-{
>-    invalidate();
>-}
>-
>-PlaybackSessionModel* PlaybackSessionInterfaceMac::playbackSessionModel() const
>+PlaybackSessionModel& PlaybackSessionInterfaceMac::playbackSessionModel() const
> {
>     return m_playbackSessionModel;
> }
>@@ -102,7 +96,7 @@ void PlaybackSessionInterfaceMac::rateChanged(bool isPlaying, float playbackRate
>     WebPlaybackControlsManager* controlsManager = playBackControlsManager();
>     [controlsManager setRate:isPlaying ? playbackRate : 0.];
>     [controlsManager setPlaying:isPlaying];
>-    updatePlaybackControlsManagerTiming(m_playbackSessionModel ? m_playbackSessionModel->currentTime() : 0, [[NSProcessInfo processInfo] systemUptime], playbackRate, isPlaying);
>+    updatePlaybackControlsManagerTiming(playbackSessionModel().currentTime(), [[NSProcessInfo processInfo] systemUptime], playbackRate, isPlaying);
> #else
>     UNUSED_PARAM(isPlaying);
>     UNUSED_PARAM(playbackRate);
>@@ -112,14 +106,14 @@ void PlaybackSessionInterfaceMac::rateChanged(bool isPlaying, float playbackRate
> void PlaybackSessionInterfaceMac::beginScrubbing()
> {
> #if ENABLE(WEB_PLAYBACK_CONTROLS_MANAGER)
>-    updatePlaybackControlsManagerTiming(m_playbackSessionModel ? m_playbackSessionModel->currentTime() : 0, [[NSProcessInfo processInfo] systemUptime], 0, false);
>+    updatePlaybackControlsManagerTiming(playbackSessionModel().currentTime(), [[NSProcessInfo processInfo] systemUptime], 0, false);
> #endif
>-    playbackSessionModel()->beginScrubbing();
>+    playbackSessionModel().beginScrubbing();
> }
> 
> void PlaybackSessionInterfaceMac::endScrubbing()
> {
>-    playbackSessionModel()->endScrubbing();
>+    playbackSessionModel().endScrubbing();
> }
> 
> #if ENABLE(WEB_PLAYBACK_CONTROLS_MANAGER)
>@@ -193,15 +187,6 @@ void PlaybackSessionInterfaceMac::externalPlaybackChanged(bool enabled, Playback
> #endif
> }
> 
>-void PlaybackSessionInterfaceMac::invalidate()
>-{
>-    if (!m_playbackSessionModel)
>-        return;
>-
>-    m_playbackSessionModel->removeClient(*this);
>-    m_playbackSessionModel = nullptr;
>-}
>-
> void PlaybackSessionInterfaceMac::ensureControlsManager()
> {
> #if ENABLE(WEB_PLAYBACK_CONTROLS_MANAGER)
>@@ -220,21 +205,21 @@ void PlaybackSessionInterfaceMac::setPlayBackControlsManager(WebPlaybackControls
> {
>     m_playbackControlsManager = manager;
> 
>-    if (!manager || !m_playbackSessionModel)
>+    if (!manager)
>         return;
> 
>     NSTimeInterval anchorTimeStamp = ![manager rate] ? NAN : [[NSProcessInfo processInfo] systemUptime];
>-    manager.timing = [getAVValueTimingClass() valueTimingWithAnchorValue:m_playbackSessionModel->currentTime() anchorTimeStamp:anchorTimeStamp rate:0];
>-    double duration = m_playbackSessionModel->duration();
>+    manager.timing = [getAVValueTimingClass() valueTimingWithAnchorValue:playbackSessionModel().currentTime() anchorTimeStamp:anchorTimeStamp rate:0];
>+    double duration = playbackSessionModel().duration();
>     manager.contentDuration = duration;
>     manager.hasEnabledAudio = duration > 0;
>     manager.hasEnabledVideo = duration > 0;
>-    manager.rate = m_playbackSessionModel->isPlaying() ? m_playbackSessionModel->playbackRate() : 0.;
>-    manager.seekableTimeRanges = timeRangesToArray(m_playbackSessionModel->seekableRanges()).get();
>+    manager.rate = playbackSessionModel().isPlaying() ? playbackSessionModel().playbackRate() : 0.;
>+    manager.seekableTimeRanges = timeRangesToArray(playbackSessionModel().seekableRanges()).get();
>     manager.canTogglePlayback = YES;
>-    manager.playing = m_playbackSessionModel->isPlaying();
>-    [manager setAudioMediaSelectionOptions:m_playbackSessionModel->audioMediaSelectionOptions() withSelectedIndex:static_cast<NSUInteger>(m_playbackSessionModel->audioMediaSelectedIndex())];
>-    [manager setLegibleMediaSelectionOptions:m_playbackSessionModel->legibleMediaSelectionOptions() withSelectedIndex:static_cast<NSUInteger>(m_playbackSessionModel->legibleMediaSelectedIndex())];
>+    manager.playing = playbackSessionModel().isPlaying();
>+    [manager setAudioMediaSelectionOptions:playbackSessionModel().audioMediaSelectionOptions() withSelectedIndex:static_cast<NSUInteger>(playbackSessionModel().audioMediaSelectedIndex())];
>+    [manager setLegibleMediaSelectionOptions:playbackSessionModel().legibleMediaSelectionOptions() withSelectedIndex:static_cast<NSUInteger>(playbackSessionModel().legibleMediaSelectedIndex())];
> }
> 
> void PlaybackSessionInterfaceMac::updatePlaybackControlsManagerTiming(double currentTime, double anchorTime, double playbackRate, bool isPlaying)
>@@ -243,16 +228,14 @@ void PlaybackSessionInterfaceMac::updatePlaybackControlsManagerTiming(double cur
>     if (!manager)
>         return;
> 
>-    PlaybackSessionModel *model = playbackSessionModel();
>-    if (!model)
>-        return;
>+    auto& model = playbackSessionModel();
> 
>     double effectiveAnchorTime = playbackRate ? anchorTime : NAN;
>     double effectivePlaybackRate = playbackRate;
>     if (!isPlaying
>-        || model->isScrubbing()
>-        || (manager.rate > 0 && model->playbackStartedTime() >= currentTime)
>-        || (manager.rate < 0 && model->playbackStartedTime() <= currentTime))
>+        || model.isScrubbing()
>+        || (manager.rate > 0 && model.playbackStartedTime() >= currentTime)
>+        || (manager.rate < 0 && model.playbackStartedTime() <= currentTime))
>         effectivePlaybackRate = 0;
> 
>     manager.timing = [getAVValueTimingClass() valueTimingWithAnchorValue:currentTime anchorTimeStamp:effectiveAnchorTime rate:effectivePlaybackRate];
>diff --git a/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.h b/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.h
>index af2c649f57e5e1585831df8b246262b2e73d6cb5..e00573a5ae6c6225737c67e87887e3bb9cfba2f6 100644
>--- a/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.h
>+++ b/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.h
>@@ -33,6 +33,7 @@
> #include "VideoFullscreenModel.h"
> #include <wtf/RefCounted.h>
> #include <wtf/RetainPtr.h>
>+#include <wtf/WeakPtr.h>
> #include <wtf/text/WTFString.h>
> 
> OBJC_CLASS NSWindow;
>@@ -46,21 +47,21 @@ class VideoFullscreenChangeObserver;
> 
> class VideoFullscreenInterfaceMac
>     : public VideoFullscreenModelClient
>-    , private PlaybackSessionModelClient
>-    , public RefCounted<VideoFullscreenInterfaceMac> {
>+    , public PlaybackSessionModelClient
>+    , public RefCounted<VideoFullscreenInterfaceMac>
>+    , public CanMakeWeakPtr<VideoFullscreenInterfaceMac> {
> 
> public:
>-    static Ref<VideoFullscreenInterfaceMac> create(PlaybackSessionInterfaceMac& playbackSessionInterface)
>+    static Ref<VideoFullscreenInterfaceMac> create(Ref<PlaybackSessionInterfaceMac>&& playbackSessionInterface, Ref<VideoFullscreenModel> videoFullscreenModel)
>     {
>-        return adoptRef(*new VideoFullscreenInterfaceMac(playbackSessionInterface));
>+        return adoptRef(*new VideoFullscreenInterfaceMac(WTFMove(playbackSessionInterface), WTFMove(videoFullscreenModel)));
>     }
>     virtual ~VideoFullscreenInterfaceMac();
>     PlaybackSessionInterfaceMac& playbackSessionInterface() const { return m_playbackSessionInterface.get(); }
>-    VideoFullscreenModel* videoFullscreenModel() const { return m_videoFullscreenModel; }
>-    PlaybackSessionModel* playbackSessionModel() const { return m_playbackSessionInterface->playbackSessionModel(); }
>-    WEBCORE_EXPORT void setVideoFullscreenModel(VideoFullscreenModel*);
>-    VideoFullscreenChangeObserver* videoFullscreenChangeObserver() const { return m_fullscreenChangeObserver; }
>-    WEBCORE_EXPORT void setVideoFullscreenChangeObserver(VideoFullscreenChangeObserver*);
>+    VideoFullscreenModel& videoFullscreenModel() const { return m_videoFullscreenModel; }
>+    PlaybackSessionModel& playbackSessionModel() const { return m_playbackSessionInterface->playbackSessionModel(); }
>+    VideoFullscreenChangeObserver* videoFullscreenChangeObserver() const { return m_fullscreenChangeObserver.get(); }
>+    WEBCORE_EXPORT void setVideoFullscreenChangeObserver(WeakPtr<VideoFullscreenChangeObserver>);
> 
>     // PlaybackSessionModelClient
>     WEBCORE_EXPORT void rateChanged(bool isPlaying, float playbackRate) override;
>@@ -97,10 +98,11 @@ public:
>     WEBCORE_EXPORT void requestHideAndExitPiP();
> 
> private:
>-    WEBCORE_EXPORT VideoFullscreenInterfaceMac(PlaybackSessionInterfaceMac&);
>+    WEBCORE_EXPORT VideoFullscreenInterfaceMac(Ref<PlaybackSessionInterfaceMac>&&, Ref<VideoFullscreenModel>&&);
>     Ref<PlaybackSessionInterfaceMac> m_playbackSessionInterface;
>-    VideoFullscreenModel* m_videoFullscreenModel { nullptr };
>-    VideoFullscreenChangeObserver* m_fullscreenChangeObserver { nullptr };
>+    Ref<VideoFullscreenModel> m_videoFullscreenModel;
>+    WeakPtrFactory<PlaybackSessionModelClient> m_weakPtrFactory;
>+    WeakPtr<VideoFullscreenChangeObserver> m_fullscreenChangeObserver;
>     HTMLMediaElementEnums::VideoFullscreenMode m_mode { HTMLMediaElementEnums::VideoFullscreenModeNone };
>     RetainPtr<WebVideoFullscreenInterfaceMacObjC> m_webVideoFullscreenInterfaceObjC;
> };
>diff --git a/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.mm b/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.mm
>index 0ae6afeade313175d2e3685cd7a2b54e8506b07b..023e765c2730447a36785f656167be64ff73b3de 100644
>--- a/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.mm
>+++ b/Source/WebCore/platform/mac/VideoFullscreenInterfaceMac.mm
>@@ -192,8 +192,8 @@ - (void)setUpPIPForVideoView:(NSView *)videoView withFrame:(NSRect)frame inWindo
>     [_pipViewController setUserCanResize:YES];
>     [_pipViewController setPlaying:_playing];
>     [self setVideoDimensions:NSEqualSizes(_videoDimensions, NSZeroSize) ? frame.size : _videoDimensions];
>-    if (_videoFullscreenInterfaceMac && _videoFullscreenInterfaceMac->videoFullscreenModel())
>-        _videoFullscreenInterfaceMac->videoFullscreenModel()->setVideoLayerGravity(VideoFullscreenModel::VideoGravityResizeAspectFill);
>+    if (_videoFullscreenInterfaceMac)
>+        _videoFullscreenInterfaceMac->videoFullscreenModel().setVideoLayerGravity(VideoFullscreenModel::VideoGravityResizeAspectFill);
> 
>     _videoViewContainer = adoptNS([[WebVideoViewContainer alloc] initWithFrame:frame]);
>     [_videoViewContainer setVideoViewContainerDelegate:self];
>@@ -246,8 +246,8 @@ - (void)boundsDidChangeForVideoViewContainer:(WebVideoViewContainer *)videoViewC
> 
>     ASSERT_UNUSED(videoViewContainer, videoViewContainer == _videoViewContainer);
> 
>-    if (_videoFullscreenInterfaceMac && _videoFullscreenInterfaceMac->videoFullscreenModel())
>-        _videoFullscreenInterfaceMac->videoFullscreenModel()->setVideoLayerFrame([_videoViewContainer bounds]);
>+    if (_videoFullscreenInterfaceMac)
>+        _videoFullscreenInterfaceMac->videoFullscreenModel().setVideoLayerFrame([_videoViewContainer bounds]);
> }
> 
> - (void)superviewDidChangeForVideoViewContainer:(WebVideoViewContainer *)videoViewContainer
>@@ -283,12 +283,12 @@ - (void)pipDidClose:(PIPViewController *)pip
> {
>     ASSERT_UNUSED(pip, pip == _pipViewController);
> 
>-    if (_videoFullscreenInterfaceMac && _videoFullscreenInterfaceMac->videoFullscreenModel() && _videoViewContainer && _returningWindow && !NSEqualRects(_returningRect, NSZeroRect)) {
>+    if (_videoFullscreenInterfaceMac && _videoViewContainer && _returningWindow && !NSEqualRects(_returningRect, NSZeroRect)) {
>         [NSAnimationContext runAnimationGroup:^(NSAnimationContext *context) {
>             context.allowsImplicitAnimation = NO;
>             [_videoViewContainer setFrame:_returningRect];
>-            _videoFullscreenInterfaceMac->videoFullscreenModel()->setVideoLayerFrame([_videoViewContainer bounds]);
>-            _videoFullscreenInterfaceMac->videoFullscreenModel()->setVideoLayerGravity(VideoFullscreenModel::VideoGravityResizeAspect);
>+            _videoFullscreenInterfaceMac->videoFullscreenModel().setVideoLayerFrame([_videoViewContainer bounds]);
>+            _videoFullscreenInterfaceMac->videoFullscreenModel().setVideoLayerGravity(VideoFullscreenModel::VideoGravityResizeAspect);
> 
>             [[_returningWindow contentView] addSubview:_videoViewContainer.get() positioned:NSWindowAbove relativeTo:nil];
>         } completionHandler:nil];
>@@ -296,10 +296,9 @@ - (void)pipDidClose:(PIPViewController *)pip
> 
>     if (_videoFullscreenInterfaceMac) {
>         if (!self.isExitingToStandardFullscreen) {
>-            if (VideoFullscreenModel* videoFullscreenModel = _videoFullscreenInterfaceMac->videoFullscreenModel()) {
>-                videoFullscreenModel->didExitPictureInPicture();
>-                videoFullscreenModel->setVideoLayerGravity(VideoFullscreenModel::VideoGravityResizeAspect);
>-            }
>+            Ref<VideoFullscreenModel> videoFullscreenModel = _videoFullscreenInterfaceMac->videoFullscreenModel();
>+            videoFullscreenModel->didExitPictureInPicture();
>+            videoFullscreenModel->setVideoLayerGravity(VideoFullscreenModel::VideoGravityResizeAspect);
>         }
> 
>         _videoFullscreenInterfaceMac->clearMode(HTMLMediaElementEnums::VideoFullscreenModePictureInPicture);
>@@ -313,16 +312,16 @@ - (void)pipActionPlay:(PIPViewController *)pip
> {
>     ASSERT_UNUSED(pip, pip == _pipViewController);
> 
>-    if (_videoFullscreenInterfaceMac && _videoFullscreenInterfaceMac->playbackSessionModel())
>-        _videoFullscreenInterfaceMac->playbackSessionModel()->play();
>+    if (_videoFullscreenInterfaceMac)
>+        _videoFullscreenInterfaceMac->playbackSessionModel().play();
> }
> 
> - (void)pipActionPause:(PIPViewController *)pip
> {
>     ASSERT_UNUSED(pip, pip == _pipViewController);
> 
>-    if (_videoFullscreenInterfaceMac && _videoFullscreenInterfaceMac->playbackSessionModel())
>-        _videoFullscreenInterfaceMac->playbackSessionModel()->pause();
>+    if (_videoFullscreenInterfaceMac)
>+        _videoFullscreenInterfaceMac->playbackSessionModel().pause();
> }
> 
> - (void)pipActionStop:(PIPViewController *)pip
>@@ -332,8 +331,7 @@ - (void)pipActionStop:(PIPViewController *)pip
>     if (!_videoFullscreenInterfaceMac)
>         return;
> 
>-    if (PlaybackSessionModel* playbackSessionModel = _videoFullscreenInterfaceMac->playbackSessionModel())
>-        playbackSessionModel->pause();
>+    _videoFullscreenInterfaceMac->playbackSessionModel().pause();
> 
>     _videoFullscreenInterfaceMac->requestHideAndExitPiP();
>     _pipState = PIPState::ExitingPIP;
>@@ -344,33 +342,23 @@ @end
> namespace WebCore {
> using namespace PAL;
> 
>-VideoFullscreenInterfaceMac::VideoFullscreenInterfaceMac(PlaybackSessionInterfaceMac& playbackSessionInterface)
>-    : m_playbackSessionInterface(playbackSessionInterface)
>+VideoFullscreenInterfaceMac::VideoFullscreenInterfaceMac(Ref<PlaybackSessionInterfaceMac>&& playbackSessionInterface, Ref<VideoFullscreenModel>&& videoFullscreenModel)
>+    : m_playbackSessionInterface(WTFMove(playbackSessionInterface))
>+    , m_videoFullscreenModel(WTFMove(videoFullscreenModel))
> {
>-    ASSERT(m_playbackSessionInterface->playbackSessionModel());
>-    auto model = m_playbackSessionInterface->playbackSessionModel();
>-    model->addClient(*this);
>-    [videoFullscreenInterfaceObjC() updateIsPlaying:model->isPlaying() newPlaybackRate:model->playbackRate()];
>+    auto& model = playbackSessionModel();
>+    model.addClient(m_weakPtrFactory.createWeakPtr(*this));
>+    [videoFullscreenInterfaceObjC() updateIsPlaying:model.isPlaying() newPlaybackRate:model.playbackRate()];
> }
> 
> VideoFullscreenInterfaceMac::~VideoFullscreenInterfaceMac()
> {
>-    if (m_playbackSessionInterface->playbackSessionModel())
>-        m_playbackSessionInterface->playbackSessionModel()->removeClient(*this);
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->removeClient(*this);
>+    auto& model = playbackSessionModel();
>+    model.removeClient(*this);
>+    m_videoFullscreenModel->removeClient(*this);
> }
> 
>-void VideoFullscreenInterfaceMac::setVideoFullscreenModel(VideoFullscreenModel* model)
>-{
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->removeClient(*this);
>-    m_videoFullscreenModel = model;
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->addClient(*this);
>-}
>-
>-void VideoFullscreenInterfaceMac::setVideoFullscreenChangeObserver(VideoFullscreenChangeObserver* observer)
>+void VideoFullscreenInterfaceMac::setVideoFullscreenChangeObserver(WeakPtr<VideoFullscreenChangeObserver> observer)
> {
>     m_fullscreenChangeObserver = observer;
> }
>@@ -382,8 +370,7 @@ void VideoFullscreenInterfaceMac::setMode(HTMLMediaElementEnums::VideoFullscreen
>         return;
> 
>     m_mode = newMode;
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->fullscreenModeChanged(m_mode);
>+    m_videoFullscreenModel->fullscreenModeChanged(m_mode);
> }
> 
> void VideoFullscreenInterfaceMac::clearMode(HTMLMediaElementEnums::VideoFullscreenMode mode)
>@@ -393,8 +380,7 @@ void VideoFullscreenInterfaceMac::clearMode(HTMLMediaElementEnums::VideoFullscre
>         return;
> 
>     m_mode = newMode;
>-    if (m_videoFullscreenModel)
>-        m_videoFullscreenModel->fullscreenModeChanged(m_mode);
>+    m_videoFullscreenModel->fullscreenModeChanged(m_mode);
> }
> 
> void VideoFullscreenInterfaceMac::rateChanged(bool isPlaying, float playbackRate)
>@@ -499,7 +485,6 @@ void VideoFullscreenInterfaceMac::invalidate()
> {
>     LOG(Fullscreen, "VideoFullscreenInterfaceMac::invalidate(%p)", this);
> 
>-    m_videoFullscreenModel = nil;
>     m_fullscreenChangeObserver = nil;
> 
>     cleanupFullscreen();
>@@ -510,9 +495,6 @@ void VideoFullscreenInterfaceMac::invalidate()
> 
> void VideoFullscreenInterfaceMac::requestHideAndExitPiP()
> {
>-    if (!m_videoFullscreenModel)
>-        return;
>-
>     m_videoFullscreenModel->requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenModeNone);
>     m_videoFullscreenModel->willExitPictureInPicture();
> }
>diff --git a/Source/WebCore/platform/mac/WebPlaybackControlsManager.mm b/Source/WebCore/platform/mac/WebPlaybackControlsManager.mm
>index b6eada31806402500602bfab0d32957da6f2b451..44691c47dd9412698c9d2d0c781b321ca84be2e1 100644
>--- a/Source/WebCore/platform/mac/WebPlaybackControlsManager.mm
>+++ b/Source/WebCore/platform/mac/WebPlaybackControlsManager.mm
>@@ -94,7 +94,7 @@ - (void)seekToTime:(NSTimeInterval)time toleranceBefore:(NSTimeInterval)toleranc
> {
>     UNUSED_PARAM(toleranceBefore);
>     UNUSED_PARAM(toleranceAfter);
>-    _playbackSessionInterfaceMac->playbackSessionModel()->seekToTime(time);
>+    _playbackSessionInterfaceMac->playbackSessionModel().seekToTime(time);
> }
> 
> - (void)cancelThumbnailAndAudioAmplitudeSampleGeneration
>@@ -193,7 +193,7 @@ - (void)setCurrentAudioTouchBarMediaSelectionOption:(AVTouchBarMediaSelectionOpt
>     if (audioMediaSelectionOption && _audioTouchBarMediaSelectionOptions)
>         index = [_audioTouchBarMediaSelectionOptions indexOfObject:audioMediaSelectionOption];
> 
>-    _playbackSessionInterfaceMac->playbackSessionModel()->selectAudioMediaOption(index != NSNotFound ? index : UINT64_MAX);
>+    _playbackSessionInterfaceMac->playbackSessionModel().selectAudioMediaOption(index != NSNotFound ? index : UINT64_MAX);
> }
> 
> - (NSArray<AVTouchBarMediaSelectionOption *> *)legibleTouchBarMediaSelectionOptions
>@@ -223,7 +223,7 @@ - (void)setCurrentLegibleTouchBarMediaSelectionOption:(AVTouchBarMediaSelectionO
>     if (legibleMediaSelectionOption && _legibleTouchBarMediaSelectionOptions)
>         index = [_legibleTouchBarMediaSelectionOptions indexOfObject:legibleMediaSelectionOption];
> 
>-    _playbackSessionInterfaceMac->playbackSessionModel()->selectLegibleMediaOption(index != NSNotFound ? index : UINT64_MAX);
>+    _playbackSessionInterfaceMac->playbackSessionModel().selectLegibleMediaOption(index != NSNotFound ? index : UINT64_MAX);
> }
> 
> #if __MAC_OS_X_VERSION_MIN_REQUIRED >= 101300
>@@ -314,26 +314,26 @@ - (void)setPlaybackSessionInterfaceMac:(PlaybackSessionInterfaceMac*)playbackSes
> 
> - (void)togglePlayback
> {
>-    if (_playbackSessionInterfaceMac && _playbackSessionInterfaceMac->playbackSessionModel())
>-        _playbackSessionInterfaceMac->playbackSessionModel()->togglePlayState();
>+    if (_playbackSessionInterfaceMac)
>+        _playbackSessionInterfaceMac->playbackSessionModel().togglePlayState();
> }
> 
> - (void)setPlaying:(BOOL)playing
> {
>-    if (!_playbackSessionInterfaceMac || !_playbackSessionInterfaceMac->playbackSessionModel())
>+    if (!_playbackSessionInterfaceMac)
>         return;
> 
>     BOOL isCurrentlyPlaying = self.playing;
>     if (!isCurrentlyPlaying && playing)
>-        _playbackSessionInterfaceMac->playbackSessionModel()->play();
>+        _playbackSessionInterfaceMac->playbackSessionModel().play();
>     else if (isCurrentlyPlaying && !playing)
>-        _playbackSessionInterfaceMac->playbackSessionModel()->pause();
>+        _playbackSessionInterfaceMac->playbackSessionModel().pause();
> }
> 
> - (BOOL)isPlaying
> {
>-    if (_playbackSessionInterfaceMac && _playbackSessionInterfaceMac->playbackSessionModel())
>-        return _playbackSessionInterfaceMac->playbackSessionModel()->isPlaying();
>+    if (_playbackSessionInterfaceMac)
>+        return _playbackSessionInterfaceMac->playbackSessionModel().isPlaying();
> 
>     return NO;
> }
>@@ -341,8 +341,8 @@ - (BOOL)isPlaying
> #if __MAC_OS_X_VERSION_MIN_REQUIRED >= 101300
> - (void)togglePictureInPicture
> {
>-    if (_playbackSessionInterfaceMac && _playbackSessionInterfaceMac->playbackSessionModel())
>-        _playbackSessionInterfaceMac->playbackSessionModel()->togglePictureInPicture();
>+    if (_playbackSessionInterfaceMac)
>+        _playbackSessionInterfaceMac->playbackSessionModel().togglePictureInPicture();
> }
> #endif
> 
>diff --git a/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.h b/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.h
>index 835bb9baf819706fdfaebece2ec0d78e53ea300b..831e431320211a89c65074ff6f67228085430307 100644
>--- a/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.h
>+++ b/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.h
>@@ -35,9 +35,10 @@
> #include <WebCore/TimeRanges.h>
> #include <wtf/HashCountedSet.h>
> #include <wtf/HashMap.h>
>-#include <wtf/HashSet.h>
> #include <wtf/RefCounted.h>
> #include <wtf/RefPtr.h>
>+#include <wtf/Vector.h>
>+#include <wtf/WeakPtrContainer.h>
> 
> #if PLATFORM(IOS)
> #include <WebCore/PlaybackSessionInterfaceAVKit.h>
>@@ -56,18 +57,20 @@ namespace WebKit {
> class WebPageProxy;
> class PlaybackSessionManagerProxy;
> 
>-class PlaybackSessionModelContext final: public RefCounted<PlaybackSessionModelContext>, public WebCore::PlaybackSessionModel  {
>+class PlaybackSessionModelContext final
>+    : public WebCore::PlaybackSessionModel
>+    , public RefCounted<PlaybackSessionModelContext> {
> public:
>-    static Ref<PlaybackSessionModelContext> create(PlaybackSessionManagerProxy& manager, uint64_t contextId)
>+    static Ref<PlaybackSessionModelContext> create(WeakPtr<PlaybackSessionManagerProxy>&& manager, uint64_t contextId)
>     {
>-        return adoptRef(*new PlaybackSessionModelContext(manager, contextId));
>+        return adoptRef(*new PlaybackSessionModelContext(WTFMove(manager), contextId));
>     }
>     virtual ~PlaybackSessionModelContext() { }
> 
>     void invalidate() { m_manager = nullptr; }
> 
>     // PlaybackSessionModel
>-    void addClient(WebCore::PlaybackSessionModelClient&) final;
>+    void addClient(WeakPtr<WebCore::PlaybackSessionModelClient>&&) final;
>     void removeClient(WebCore::PlaybackSessionModelClient&)final;
> 
>     void durationChanged(double);
>@@ -87,16 +90,21 @@ public:
>     void volumeChanged(double);
>     void pictureInPictureActiveChanged(bool);
> 
>+    using RefCounted::ref;
>+    using RefCounted::deref;
>+
> private:
>     friend class VideoFullscreenModelContext;
> 
>-    PlaybackSessionModelContext(PlaybackSessionManagerProxy& manager, uint64_t contextId)
>-        : m_manager(&manager)
>+    PlaybackSessionModelContext(WeakPtr<PlaybackSessionManagerProxy>&& manager, uint64_t contextId)
>+        : m_manager(WTFMove(manager))
>         , m_contextId(contextId)
>     {
>     }
> 
>     // PlaybackSessionModel
>+    void refPlaybackSessionModel() final { ref(); }
>+    void derefPlaybackSessionModel() final { deref(); }
>     void play() final;
>     void pause() final;
>     void togglePlayState() final;
>@@ -136,10 +144,10 @@ private:
>     bool isMuted() const final { return m_muted; }
>     double volume() const final { return m_volume; }
>     bool isPictureInPictureActive() const final { return m_pictureInPictureActive; }
>-
>-    PlaybackSessionManagerProxy* m_manager;
>+    
>+    WeakPtr<PlaybackSessionManagerProxy> m_manager;
>     uint64_t m_contextId;
>-    HashSet<WebCore::PlaybackSessionModelClient*> m_clients;
>+    WeakPtrContainer<WebCore::PlaybackSessionModelClient> m_clients;
>     double m_playbackStartedTime { 0 };
>     bool m_playbackStartedTimeNeedsUpdate { false };
>     double m_duration { 0 };
>@@ -165,7 +173,10 @@ private:
>     bool m_pictureInPictureActive { false };
> };
> 
>-class PlaybackSessionManagerProxy : public RefCounted<PlaybackSessionManagerProxy>, private IPC::MessageReceiver {
>+class PlaybackSessionManagerProxy
>+    : public RefCounted<PlaybackSessionManagerProxy>
>+    , private IPC::MessageReceiver
>+    , public CanMakeWeakPtr<PlaybackSessionManagerProxy> {
> public:
>     static RefPtr<PlaybackSessionManagerProxy> create(WebPageProxy&);
>     virtual ~PlaybackSessionManagerProxy();
>diff --git a/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.mm b/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.mm
>index f4c7066c1e6ead8a80fbb35331b63bc4795384e6..860e2d44be8f4bfcdd226ae0e6695856f3d31109 100644
>--- a/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.mm
>+++ b/Source/WebKit/UIProcess/Cocoa/PlaybackSessionManagerProxy.mm
>@@ -39,16 +39,14 @@ namespace WebKit {
> 
> #pragma mark - PlaybackSessionModelContext
> 
>-void PlaybackSessionModelContext::addClient(PlaybackSessionModelClient& client)
>+void PlaybackSessionModelContext::addClient(WeakPtr<PlaybackSessionModelClient>&& client)
> {
>-    ASSERT(!m_clients.contains(&client));
>-    m_clients.add(&client);
>+    m_clients.add(WTFMove(client));
> }
> 
> void PlaybackSessionModelContext::removeClient(PlaybackSessionModelClient& client)
> {
>-    ASSERT(m_clients.contains(&client));
>-    m_clients.remove(&client);
>+    m_clients.remove(client);
> }
> 
> void PlaybackSessionModelContext::play()
>@@ -161,8 +159,9 @@ void PlaybackSessionModelContext::playbackStartedTimeChanged(double playbackStar
> void PlaybackSessionModelContext::durationChanged(double duration)
> {
>     m_duration = duration;
>-    for (auto* client : m_clients)
>-        client->durationChanged(duration);
>+    m_clients.forEachNonNullMember([duration] (auto& client) {
>+        client.durationChanged(duration);
>+    });
> }
> 
> void PlaybackSessionModelContext::currentTimeChanged(double currentTime)
>@@ -172,23 +171,26 @@ void PlaybackSessionModelContext::currentTimeChanged(double currentTime)
>     if (m_playbackStartedTimeNeedsUpdate)
>         playbackStartedTimeChanged(currentTime);
> 
>-    for (auto* client : m_clients)
>-        client->currentTimeChanged(currentTime, anchorTime);
>+    m_clients.forEachNonNullMember([currentTime, anchorTime] (auto& client) {
>+        client.currentTimeChanged(currentTime, anchorTime);
>+    });
> }
> 
> void PlaybackSessionModelContext::bufferedTimeChanged(double bufferedTime)
> {
>     m_bufferedTime = bufferedTime;
>-    for (auto* client : m_clients)
>-        client->bufferedTimeChanged(bufferedTime);
>+    m_clients.forEachNonNullMember([bufferedTime] (auto& client) {
>+        client.bufferedTimeChanged(bufferedTime);
>+    });
> }
> 
> void PlaybackSessionModelContext::rateChanged(bool isPlaying, float playbackRate)
> {
>     m_isPlaying = isPlaying;
>     m_playbackRate = playbackRate;
>-    for (auto* client : m_clients)
>-        client->rateChanged(isPlaying, playbackRate);
>+    m_clients.forEachNonNullMember([isPlaying, playbackRate] (auto& client) {
>+        client.rateChanged(isPlaying, playbackRate);
>+    });
> }
> 
> void PlaybackSessionModelContext::seekableRangesChanged(WebCore::TimeRanges& seekableRanges, double lastModifiedTime, double liveUpdateInterval)
>@@ -196,23 +198,26 @@ void PlaybackSessionModelContext::seekableRangesChanged(WebCore::TimeRanges& see
>     m_seekableRanges = seekableRanges;
>     m_seekableTimeRangesLastModifiedTime = lastModifiedTime;
>     m_liveUpdateInterval = liveUpdateInterval;
>-    for (auto* client : m_clients)
>-        client->seekableRangesChanged(seekableRanges, lastModifiedTime, liveUpdateInterval);
>+    m_clients.forEachNonNullMember([seekableRanges = makeRef(seekableRanges), lastModifiedTime, liveUpdateInterval] (auto& client) {
>+        client.seekableRangesChanged(seekableRanges, lastModifiedTime, liveUpdateInterval);
>+    });
> }
> 
> void PlaybackSessionModelContext::canPlayFastReverseChanged(bool canPlayFastReverse)
> {
>     m_canPlayFastReverse = canPlayFastReverse;
>-    for (auto* client : m_clients)
>-        client->canPlayFastReverseChanged(canPlayFastReverse);
>+    m_clients.forEachNonNullMember([canPlayFastReverse] (auto& client) {
>+        client.canPlayFastReverseChanged(canPlayFastReverse);
>+    });
> }
> 
> void PlaybackSessionModelContext::audioMediaSelectionOptionsChanged(const Vector<MediaSelectionOption>& audioMediaSelectionOptions, uint64_t audioMediaSelectedIndex)
> {
>     m_audioMediaSelectionOptions = audioMediaSelectionOptions;
>     m_audioMediaSelectedIndex = audioMediaSelectedIndex;
>-    for (auto* client : m_clients)
>-        client->audioMediaSelectionOptionsChanged(audioMediaSelectionOptions, audioMediaSelectedIndex);
>+    m_clients.forEachNonNullMember([audioMediaSelectionOptions, audioMediaSelectedIndex] (auto& client) {
>+        client.audioMediaSelectionOptionsChanged(audioMediaSelectionOptions, audioMediaSelectedIndex);
>+    });
> }
> 
> void PlaybackSessionModelContext::legibleMediaSelectionOptionsChanged(const Vector<MediaSelectionOption>& legibleMediaSelectionOptions, uint64_t legibleMediaSelectedIndex)
>@@ -220,24 +225,27 @@ void PlaybackSessionModelContext::legibleMediaSelectionOptionsChanged(const Vect
>     m_legibleMediaSelectionOptions = legibleMediaSelectionOptions;
>     m_legibleMediaSelectedIndex = legibleMediaSelectedIndex;
> 
>-    for (auto* client : m_clients)
>-        client->legibleMediaSelectionOptionsChanged(legibleMediaSelectionOptions, legibleMediaSelectedIndex);
>+    m_clients.forEachNonNullMember([legibleMediaSelectionOptions, legibleMediaSelectedIndex] (auto& client) {
>+        client.legibleMediaSelectionOptionsChanged(legibleMediaSelectionOptions, legibleMediaSelectedIndex);
>+    });
> }
> 
> void PlaybackSessionModelContext::audioMediaSelectionIndexChanged(uint64_t selectedIndex)
> {
>     m_audioMediaSelectedIndex = selectedIndex;
> 
>-    for (auto* client : m_clients)
>-        client->audioMediaSelectionIndexChanged(selectedIndex);
>+    m_clients.forEachNonNullMember([selectedIndex] (auto& client) {
>+        client.audioMediaSelectionIndexChanged(selectedIndex);
>+    });
> }
> 
> void PlaybackSessionModelContext::legibleMediaSelectionIndexChanged(uint64_t selectedIndex)
> {
>     m_legibleMediaSelectedIndex = selectedIndex;
> 
>-    for (auto* client : m_clients)
>-        client->legibleMediaSelectionIndexChanged(selectedIndex);
>+    m_clients.forEachNonNullMember([selectedIndex] (auto& client) {
>+        client.legibleMediaSelectionIndexChanged(selectedIndex);
>+    });
> }
> 
> void PlaybackSessionModelContext::externalPlaybackChanged(bool enabled, PlaybackSessionModel::ExternalPlaybackTargetType type, const String& localizedName)
>@@ -246,36 +254,41 @@ void PlaybackSessionModelContext::externalPlaybackChanged(bool enabled, Playback
>     m_externalPlaybackTargetType = type;
>     m_externalPlaybackLocalizedDeviceName = localizedName;
> 
>-    for (auto* client : m_clients)
>-        client->externalPlaybackChanged(enabled, type, localizedName);
>+    m_clients.forEachNonNullMember([enabled, type, localizedName] (auto& client) {
>+        client.externalPlaybackChanged(enabled, type, localizedName);
>+    });
> }
> 
> void PlaybackSessionModelContext::wirelessVideoPlaybackDisabledChanged(bool wirelessVideoPlaybackDisabled)
> {
>     m_wirelessVideoPlaybackDisabled = wirelessVideoPlaybackDisabled;
>-    for (auto* client : m_clients)
>-        client->wirelessVideoPlaybackDisabledChanged(wirelessVideoPlaybackDisabled);
>+    m_clients.forEachNonNullMember([wirelessVideoPlaybackDisabled] (auto& client) {
>+        client.wirelessVideoPlaybackDisabledChanged(wirelessVideoPlaybackDisabled);
>+    });
> }
> 
> void PlaybackSessionModelContext::mutedChanged(bool muted)
> {
>     m_muted = muted;
>-    for (auto* client : m_clients)
>-        client->mutedChanged(muted);
>+    m_clients.forEachNonNullMember([muted] (auto& client) {
>+        client.mutedChanged(muted);
>+    });
> }
> 
> void PlaybackSessionModelContext::volumeChanged(double volume)
> {
>     m_volume = volume;
>-    for (auto* client : m_clients)
>-        client->volumeChanged(volume);
>+    m_clients.forEachNonNullMember([volume] (auto& client) {
>+        client.volumeChanged(volume);
>+    });
> }
> 
> void PlaybackSessionModelContext::pictureInPictureActiveChanged(bool active)
> {
>     m_pictureInPictureActive = active;
>-    for (auto* client : m_clients)
>-        client->pictureInPictureActiveChanged(active);
>+    m_clients.forEachNonNullMember([active] (auto& client) {
>+        client.pictureInPictureActiveChanged(active);
>+    });
> }
> 
> #pragma mark - PlaybackSessionManagerProxy
>@@ -303,22 +316,14 @@ void PlaybackSessionManagerProxy::invalidate()
>     m_page->process().removeMessageReceiver(Messages::PlaybackSessionManagerProxy::messageReceiverName(), m_page->pageID());
>     m_page = nullptr;
> 
>-    auto contextMap = WTFMove(m_contextMap);
>+    m_contextMap.clear();
>     m_clientCounts.clear();
>-
>-    for (auto& tuple : contextMap.values()) {
>-        RefPtr<PlaybackSessionModelContext> model;
>-        RefPtr<PlatformPlaybackSessionInterface> interface;
>-        std::tie(model, interface) = tuple;
>-
>-        interface->invalidate();
>-    }
> }
> 
> PlaybackSessionManagerProxy::ModelInterfaceTuple PlaybackSessionManagerProxy::createModelAndInterface(uint64_t contextId)
> {
>-    Ref<PlaybackSessionModelContext> model = PlaybackSessionModelContext::create(*this, contextId);
>-    Ref<PlatformPlaybackSessionInterface> interface = PlatformPlaybackSessionInterface::create(model);
>+    Ref<PlaybackSessionModelContext> model = PlaybackSessionModelContext::create(makeWeakPtr(this), contextId);
>+    Ref<PlatformPlaybackSessionInterface> interface = PlatformPlaybackSessionInterface::create(model.copyRef());
> 
>     return std::make_tuple(WTFMove(model), WTFMove(interface));
> }
>@@ -348,11 +353,8 @@ void PlaybackSessionManagerProxy::addClientForContext(uint64_t contextId)
> 
> void PlaybackSessionManagerProxy::removeClientForContext(uint64_t contextId)
> {
>-    if (!m_clientCounts.remove(contextId))
>-        return;
>-
>-    ensureInterface(contextId).invalidate();
>-    m_contextMap.remove(contextId);
>+    if (m_clientCounts.remove(contextId))
>+        m_contextMap.remove(contextId);
> }
> 
> #pragma mark Messages from PlaybackSessionManager
>diff --git a/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.h b/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.h
>index 48663c252ba878bba1a191403c2ccaee31610916..b6f74f5d41b746227c96d783c230ed515862c0ab 100644
>--- a/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.h
>+++ b/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.h
>@@ -33,9 +33,11 @@
> #include <WebCore/VideoFullscreenChangeObserver.h>
> #include <WebCore/VideoFullscreenModel.h>
> #include <wtf/HashMap.h>
>-#include <wtf/HashSet.h>
> #include <wtf/RefCounted.h>
> #include <wtf/RefPtr.h>
>+#include <wtf/UniqueRef.h>
>+#include <wtf/Vector.h>
>+#include <wtf/WeakPtrContainer.h>
> 
> #if PLATFORM(IOS)
> #include <WebCore/VideoFullscreenInterfaceAVKit.h>
>@@ -59,12 +61,9 @@ class VideoFullscreenManagerProxy;
> class VideoFullscreenModelContext final
>     : public RefCounted<VideoFullscreenModelContext>
>     , public WebCore::VideoFullscreenModel
>-    , public WebCore::VideoFullscreenChangeObserver  {
>+    , public WebCore::VideoFullscreenChangeObserver {
> public:
>-    static Ref<VideoFullscreenModelContext> create(VideoFullscreenManagerProxy& manager, PlaybackSessionModelContext& playbackSessionModel, uint64_t contextId)
>-    {
>-        return adoptRef(*new VideoFullscreenModelContext(manager, playbackSessionModel, contextId));
>-    }
>+    static Ref<VideoFullscreenModelContext> create(WeakPtr<VideoFullscreenManagerProxy>&&, Ref<PlaybackSessionModelContext>&&, uint64_t contextId);
>     virtual ~VideoFullscreenModelContext();
> 
>     void invalidate() { m_manager = nullptr; }
>@@ -72,19 +71,26 @@ public:
>     PlatformView *layerHostView() const { return m_layerHostView.get(); }
>     void setLayerHostView(RetainPtr<PlatformView>&& layerHostView) { m_layerHostView = WTFMove(layerHostView); }
> 
>+    WeakPtr<VideoFullscreenChangeObserver> createWeakPtr() { return m_weakPtrFactory.createWeakPtr(*this); }
>+
>+    using RefCounted::ref;
>+    using RefCounted::deref;
>+
> private:
>-    VideoFullscreenModelContext(VideoFullscreenManagerProxy&, PlaybackSessionModelContext&, uint64_t);
>+    VideoFullscreenModelContext(WeakPtr<VideoFullscreenManagerProxy>&&, Ref<PlaybackSessionModelContext>&&, uint64_t);
> 
>     // VideoFullscreenModel
>-    void addClient(WebCore::VideoFullscreenModelClient&) override;
>-    void removeClient(WebCore::VideoFullscreenModelClient&) override;
>-    void requestFullscreenMode(WebCore::HTMLMediaElementEnums::VideoFullscreenMode, bool finishedWithMedia = false) override;
>-    void setVideoLayerFrame(WebCore::FloatRect) override;
>-    void setVideoLayerGravity(VideoGravity) override;
>-    void fullscreenModeChanged(WebCore::HTMLMediaElementEnums::VideoFullscreenMode) override;
>-    bool isVisible() const override;
>-    bool hasVideo() const override { return m_hasVideo; }
>-    WebCore::FloatSize videoDimensions() const override { return m_videoDimensions; }
>+    void refVideoFullscreenModel() final { ref(); }
>+    void derefVideoFullscreenModel() final { deref(); }
>+    void addClient(WeakPtr<WebCore::VideoFullscreenModelClient>&&) final;
>+    void removeClient(WebCore::VideoFullscreenModelClient&) final;
>+    void requestFullscreenMode(WebCore::HTMLMediaElementEnums::VideoFullscreenMode, bool finishedWithMedia = false) final;
>+    void setVideoLayerFrame(WebCore::FloatRect) final;
>+    void setVideoLayerGravity(VideoGravity) final;
>+    void fullscreenModeChanged(WebCore::HTMLMediaElementEnums::VideoFullscreenMode) final;
>+    bool isVisible() const final;
>+    bool hasVideo() const final { return m_hasVideo; }
>+    WebCore::FloatSize videoDimensions() const final { return m_videoDimensions; }
> #if PLATFORM(IOS)
>     UIViewController *presentingViewController() final;
>     UIViewController *createVideoFullscreenViewController(AVPlayerViewController*) final;
>@@ -106,16 +112,20 @@ private:
>     void didCleanupFullscreen() final;
>     void fullscreenMayReturnToInline() final;
> 
>-    VideoFullscreenManagerProxy* m_manager;
>+    WeakPtr<VideoFullscreenManagerProxy> m_manager;
>     Ref<PlaybackSessionModelContext> m_playbackSessionModel;
>     uint64_t m_contextId;
>+    WeakPtrFactory<VideoFullscreenChangeObserver> m_weakPtrFactory;
>     RetainPtr<PlatformView *> m_layerHostView;
>-    HashSet<WebCore::VideoFullscreenModelClient*> m_clients;
>+    WeakPtrContainer<WebCore::VideoFullscreenModelClient> m_clients;
>     WebCore::FloatSize m_videoDimensions;
>     bool m_hasVideo { false };
> };
> 
>-class VideoFullscreenManagerProxy : public RefCounted<VideoFullscreenManagerProxy>, private IPC::MessageReceiver {
>+class VideoFullscreenManagerProxy
>+    : public RefCounted<VideoFullscreenManagerProxy>
>+    , private IPC::MessageReceiver 
>+    , public CanMakeWeakPtr<VideoFullscreenManagerProxy> {
> public:
>     static RefPtr<VideoFullscreenManagerProxy> create(WebPageProxy&, PlaybackSessionManagerProxy&);
>     virtual ~VideoFullscreenManagerProxy();
>diff --git a/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.mm b/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.mm
>index 9100afd8c41120bb5e581d230a2476f7542fed22..596c9c378f612498afdd3ce7e49ab0ae1076e9d6 100644
>--- a/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.mm
>+++ b/Source/WebKit/UIProcess/Cocoa/VideoFullscreenManagerProxy.mm
>@@ -161,27 +161,28 @@ void VideoFullscreenManagerProxy::applicationDidBecomeActive()
> 
> #pragma mark - VideoFullscreenModelContext
> 
>-VideoFullscreenModelContext::VideoFullscreenModelContext(VideoFullscreenManagerProxy& manager, PlaybackSessionModelContext& playbackSessionModel, uint64_t contextId)
>-    : m_manager(&manager)
>-    , m_playbackSessionModel(playbackSessionModel)
>-    , m_contextId(contextId)
>+Ref<VideoFullscreenModelContext> VideoFullscreenModelContext::create(WeakPtr<VideoFullscreenManagerProxy>&& manager, Ref<PlaybackSessionModelContext>&& playbackSessionModel, uint64_t contextId)
> {
>+    return adoptRef(*new VideoFullscreenModelContext(WTFMove(manager), WTFMove(playbackSessionModel), contextId));
> }
> 
>-VideoFullscreenModelContext::~VideoFullscreenModelContext()
>+VideoFullscreenModelContext::VideoFullscreenModelContext(WeakPtr<VideoFullscreenManagerProxy>&& manager, Ref<PlaybackSessionModelContext>&& playbackSessionModel, uint64_t contextId)
>+    : m_manager(WTFMove(manager))
>+    , m_playbackSessionModel(WTFMove(playbackSessionModel))
>+    , m_contextId(contextId)
> {
> }
> 
>-void VideoFullscreenModelContext::addClient(VideoFullscreenModelClient& client)
>+VideoFullscreenModelContext::~VideoFullscreenModelContext() = default;
>+
>+void VideoFullscreenModelContext::addClient(WeakPtr<VideoFullscreenModelClient>&& client)
> {
>-    ASSERT(!m_clients.contains(&client));
>-    m_clients.add(&client);
>+    m_clients.add(WTFMove(client));
> }
> 
> void VideoFullscreenModelContext::removeClient(VideoFullscreenModelClient& client)
> {
>-    ASSERT(m_clients.contains(&client));
>-    m_clients.remove(&client);
>+    m_clients.remove(client);
> }
> 
> void VideoFullscreenModelContext::requestFullscreenMode(HTMLMediaElementEnums::VideoFullscreenMode mode, bool finishedWithMedia)
>@@ -284,32 +285,37 @@ void VideoFullscreenModelContext::fullscreenMayReturnToInline()
> 
> void VideoFullscreenModelContext::willEnterPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->willEnterPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.willEnterPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelContext::didEnterPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->didEnterPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.didEnterPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelContext::failedToEnterPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->failedToEnterPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.failedToEnterPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelContext::willExitPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->willExitPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.willExitPictureInPicture();
>+    });
> }
> 
> void VideoFullscreenModelContext::didExitPictureInPicture()
> {
>-    for (auto& client : m_clients)
>-        client->didExitPictureInPicture();
>+    m_clients.forEachNonNullMember([] (auto& client) {
>+        client.didExitPictureInPicture();
>+    });
> }
> 
> #pragma mark - VideoFullscreenManagerProxy
>@@ -346,7 +352,6 @@ void VideoFullscreenManagerProxy::invalidate()
>         RefPtr<PlatformVideoFullscreenInterface> interface;
>         std::tie(model, interface) = tuple;
> 
>-        interface->invalidate();
>         [model->layerHostView() removeFromSuperview];
>         model->setLayerHostView(nullptr);
>     }
>@@ -404,13 +409,12 @@ void VideoFullscreenManagerProxy::applicationDidBecomeActive()
> VideoFullscreenManagerProxy::ModelInterfaceTuple VideoFullscreenManagerProxy::createModelAndInterface(uint64_t contextId)
> {
>     auto& playbackSessionModel = m_playbackSessionManagerProxy->ensureModel(contextId);
>-    Ref<VideoFullscreenModelContext> model = VideoFullscreenModelContext::create(*this, playbackSessionModel, contextId);
>     auto& playbackSessionInterface = m_playbackSessionManagerProxy->ensureInterface(contextId);
>-    Ref<PlatformVideoFullscreenInterface> interface = PlatformVideoFullscreenInterface::create(playbackSessionInterface);
>+    Ref<VideoFullscreenModelContext> model = VideoFullscreenModelContext::create(makeWeakPtr(this), playbackSessionModel, contextId);
>+    Ref<PlatformVideoFullscreenInterface> interface = PlatformVideoFullscreenInterface::create(makeRef(playbackSessionInterface), model.copyRef());
>     m_playbackSessionManagerProxy->addClientForContext(contextId);
> 
>-    interface->setVideoFullscreenModel(&model.get());
>-    interface->setVideoFullscreenChangeObserver(&model.get());
>+    interface->setVideoFullscreenChangeObserver(model->createWeakPtr());
> 
>     return std::make_tuple(WTFMove(model), WTFMove(interface));
> }
>@@ -449,7 +453,6 @@ void VideoFullscreenManagerProxy::removeClientForContext(uint64_t contextId)
>     clientCount--;
> 
>     if (clientCount <= 0) {
>-        ensureInterface(contextId).setVideoFullscreenModel(nullptr);
>         m_playbackSessionManagerProxy->removeClientForContext(contextId);
>         m_clientCounts.remove(contextId);
>         m_contextMap.remove(contextId);
>diff --git a/Source/WebKit/UIProcess/ios/fullscreen/WKFullScreenViewController.mm b/Source/WebKit/UIProcess/ios/fullscreen/WKFullScreenViewController.mm
>index d88d63d86e7e06eddcaaf66664eaff2af3553662..b612d0c18eabf44886b7841a68ab57f4ca970514 100644
>--- a/Source/WebKit/UIProcess/ios/fullscreen/WKFullScreenViewController.mm
>+++ b/Source/WebKit/UIProcess/ios/fullscreen/WKFullScreenViewController.mm
>@@ -56,7 +56,9 @@ - (void)didEnterPictureInPicture;
> - (void)failedToEnterPictureInPicture;
> @end
> 
>-class WKFullScreenViewControllerPlaybackSessionModelClient : PlaybackSessionModelClient {
>+class WKFullScreenViewControllerPlaybackSessionModelClient 
>+    : public PlaybackSessionModelClient
>+    , public CanMakeWeakPtr<WKFullScreenViewControllerPlaybackSessionModelClient> {
> public:
>     void setParent(WKFullScreenViewController *parent) { m_parent = parent; }
> 
>@@ -75,11 +77,11 @@ public:
>         if (m_interface == interface)
>             return;
> 
>-        if (m_interface && m_interface->playbackSessionModel())
>-            m_interface->playbackSessionModel()->removeClient(*this);
>+        if (m_interface)
>+            m_interface->playbackSessionModel().removeClient(*this);
>         m_interface = interface;
>-        if (m_interface && m_interface->playbackSessionModel())
>-            m_interface->playbackSessionModel()->addClient(*this);
>+        if (m_interface)
>+            m_interface->playbackSessionModel().addClient(makeWeakPtr(*this));
>     }
> 
> private:
>@@ -87,7 +89,9 @@ private:
>     RefPtr<PlaybackSessionInterfaceAVKit> m_interface;
> };
> 
>-class WKFullScreenViewControllerVideoFullscreenModelClient : VideoFullscreenModelClient {
>+class WKFullScreenViewControllerVideoFullscreenModelClient
>+    : public VideoFullscreenModelClient
>+    , public CanMakeWeakPtr<WKFullScreenViewControllerVideoFullscreenModelClient> {
> public:
>     void setParent(WKFullScreenViewController *parent) { m_parent = parent; }
> 
>@@ -96,11 +100,11 @@ public:
>         if (m_interface == interface)
>             return;
> 
>-        if (m_interface && m_interface->videoFullscreenModel())
>-            m_interface->videoFullscreenModel()->removeClient(*this);
>+        if (m_interface)
>+            m_interface->videoFullscreenModel().removeClient(*this);
>         m_interface = interface;
>-        if (m_interface && m_interface->videoFullscreenModel())
>-            m_interface->videoFullscreenModel()->addClient(*this);
>+        if (m_interface)
>+            m_interface->videoFullscreenModel().addClient(makeWeakPtr(*this));
>     }
> 
>     VideoFullscreenInterfaceAVKit* interface() const { return m_interface.get(); }
>@@ -264,9 +268,14 @@ - (void)videoControlsManagerDidChange
>     _playbackClient.setInterface(playbackSessionInterface);
>     _videoFullscreenClient.setInterface(videoFullscreenInterface);
> 
>-    PlaybackSessionModel* playbackSessionModel = playbackSessionInterface ? playbackSessionInterface->playbackSessionModel() : nullptr;
>-    self.playing = playbackSessionModel ? playbackSessionModel->isPlaying() : NO;
>-    [_pipButton setHidden:!playbackSessionModel];
>+    if (!playbackSessionInterface) {
>+        self.playing = NO;
>+        [_pipButton setHidden:YES];
>+        return;
>+    }
>+
>+    self.playing = playbackSessionInterface->playbackSessionModel().isPlaying();
>+    [_pipButton setHidden:NO];
> }
> 
> - (void)setPrefersStatusBarHidden:(BOOL)value
>@@ -512,14 +521,8 @@ - (void)_togglePiPAction:(id)sender
>         return;
> 
>     PlatformPlaybackSessionInterface* playbackSessionInterface = playbackSessionManager->controlsManagerInterface();
>-    if (!playbackSessionInterface)
>-        return;
>-
>-    PlaybackSessionModel* playbackSessionModel = playbackSessionInterface->playbackSessionModel();
>-    if (!playbackSessionModel)
>-        return;
>-
>-    playbackSessionModel->togglePictureInPicture();
>+    if (playbackSessionInterface)
>+        playbackSessionInterface->playbackSessionModel().togglePictureInPicture();
> }
> 
> - (void)_touchDetected:(id)sender
>diff --git a/Source/WebKit/UIProcess/mac/WKFullScreenWindowController.mm b/Source/WebKit/UIProcess/mac/WKFullScreenWindowController.mm
>index 47251d82fb33984d7f7f2a2f6c248ef857f2cc90..baabe1aacfecafa1c9becb214e84a6dee21c8136 100644
>--- a/Source/WebKit/UIProcess/mac/WKFullScreenWindowController.mm
>+++ b/Source/WebKit/UIProcess/mac/WKFullScreenWindowController.mm
>@@ -54,7 +54,9 @@ static const NSTimeInterval DefaultWatchdogTimerInterval = 1;
> 
> namespace WebKit {
> 
>-class WKFullScreenWindowControllerVideoFullscreenModelClient : VideoFullscreenModelClient {
>+class WKFullScreenWindowControllerVideoFullscreenModelClient 
>+    : public CanMakeWeakPtr<WKFullScreenWindowControllerVideoFullscreenModelClient>
>+    , public VideoFullscreenModelClient {
> public:
>     void setParent(WKFullScreenWindowController *parent) { m_parent = parent; }
> 
>@@ -63,11 +65,11 @@ public:
>         if (m_interface == interface)
>             return;
> 
>-        if (m_interface && m_interface->videoFullscreenModel())
>-            m_interface->videoFullscreenModel()->removeClient(*this);
>+        if (m_interface)
>+            m_interface->videoFullscreenModel().removeClient(*this);
>         m_interface = interface;
>-        if (m_interface && m_interface->videoFullscreenModel())
>-            m_interface->videoFullscreenModel()->addClient(*this);
>+        if (m_interface)
>+            m_interface->videoFullscreenModel().addClient(makeWeakPtr(this));
>     }
> 
>     VideoFullscreenInterfaceMac* interface() const { return m_interface.get(); }
>diff --git a/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.h b/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.h
>index d297dac2297fff9ab88f6180b9e9d928e502812f..c8c6254ecb8d71853fcff87730b09a5ebb517b1c 100644
>--- a/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.h
>+++ b/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.h
>@@ -47,6 +47,8 @@ class MessageReceiver;
> 
> namespace WebCore {
> class Node;
>+class PlaybackSessionModel;
>+class PlaybackSessionModelClient;
> }
> 
> namespace WebKit {
>@@ -55,17 +57,17 @@ class WebPage;
> class PlaybackSessionManager;
> 
> class PlaybackSessionInterfaceContext final
>-    : public RefCounted<PlaybackSessionInterfaceContext>
>-    , public WebCore::PlaybackSessionInterface
>-    , public WebCore::PlaybackSessionModelClient {
>+    : public WebCore::PlaybackSessionInterface
>+    , public WebCore::PlaybackSessionModelClient
>+    , public RefCounted<PlaybackSessionInterfaceContext> {
> public:
>-    static Ref<PlaybackSessionInterfaceContext> create(PlaybackSessionManager& manager, uint64_t contextId)
>+    static Ref<PlaybackSessionInterfaceContext> create(WeakPtr<PlaybackSessionManager>&& manager, uint64_t contextId)
>     {
>-        return adoptRef(*new PlaybackSessionInterfaceContext(manager, contextId));
>+        return adoptRef(*new PlaybackSessionInterfaceContext(WTFMove(manager), contextId));
>     }
>     virtual ~PlaybackSessionInterfaceContext();
> 
>-    void invalidate() { m_manager = nullptr; }
>+    WeakPtr<WebCore::PlaybackSessionModelClient> createWeakPtr() { return m_weakPtrFactory.createWeakPtr(*this); }
> 
> private:
>     friend class VideoFullscreenInterfaceContext;
>@@ -90,13 +92,17 @@ private:
>     void mutedChanged(bool) final;
>     void volumeChanged(double) final;
> 
>-    PlaybackSessionInterfaceContext(PlaybackSessionManager&, uint64_t contextId);
>+    PlaybackSessionInterfaceContext(WeakPtr<PlaybackSessionManager>&&, uint64_t contextId);
> 
>-    PlaybackSessionManager* m_manager;
>+    WeakPtr<PlaybackSessionManager> m_manager;
>+    WeakPtrFactory<PlaybackSessionModelClient> m_weakPtrFactory;
>     uint64_t m_contextId;
> };
> 
>-class PlaybackSessionManager : public RefCounted<PlaybackSessionManager>, private IPC::MessageReceiver {
>+class PlaybackSessionManager
>+    : public RefCounted<PlaybackSessionManager>
>+    , private IPC::MessageReceiver
>+    , public CanMakeWeakPtr<PlaybackSessionManager> {
> public:
>     static Ref<PlaybackSessionManager> create(WebPage&);
>     virtual ~PlaybackSessionManager();
>@@ -163,6 +169,7 @@ protected:
>     void setMuted(uint64_t contextId, bool muted);
>     void setVolume(uint64_t contextId, double volume);
> 
>+    WeakPtrFactory<WebCore::PlaybackSessionModel> m_weakPtrFactory;
>     WebPage* m_page;
>     HashMap<WebCore::HTMLMediaElement*, uint64_t> m_mediaElements;
>     HashMap<uint64_t, ModelInterfaceTuple> m_contextMap;
>diff --git a/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.mm b/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.mm
>index b010d3076b0b30c98050319091bf7093f8c027b4..465faf76aa3d85f15f5866b1da4db9e36903167d 100644
>--- a/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.mm
>+++ b/Source/WebKit/WebProcess/cocoa/PlaybackSessionManager.mm
>@@ -55,15 +55,13 @@ static uint64_t nextContextId()
> 
> #pragma mark - PlaybackSessionInterfaceContext
> 
>-PlaybackSessionInterfaceContext::PlaybackSessionInterfaceContext(PlaybackSessionManager& manager, uint64_t contextId)
>-    : m_manager(&manager)
>+PlaybackSessionInterfaceContext::PlaybackSessionInterfaceContext(WeakPtr<PlaybackSessionManager>&& manager, uint64_t contextId)
>+    : m_manager(WTFMove(manager))
>     , m_contextId(contextId)
> {
> }
> 
>-PlaybackSessionInterfaceContext::~PlaybackSessionInterfaceContext()
>-{
>-}
>+PlaybackSessionInterfaceContext::~PlaybackSessionInterfaceContext() = default;
> 
> void PlaybackSessionInterfaceContext::resetMediaState()
> {
>@@ -180,10 +178,7 @@ PlaybackSessionManager::~PlaybackSessionManager()
>         RefPtr<PlaybackSessionModelMediaElement> model;
>         RefPtr<PlaybackSessionInterfaceContext> interface;
>         std::tie(model, interface) = tuple;
>-        model->removeClient(*interface);
>         model->setMediaElement(nullptr);
>-
>-        interface->invalidate();
>     }
> 
>     m_contextMap.clear();
>@@ -203,9 +198,9 @@ void PlaybackSessionManager::invalidate()
> 
> PlaybackSessionManager::ModelInterfaceTuple PlaybackSessionManager::createModelAndInterface(uint64_t contextId)
> {
>-    RefPtr<PlaybackSessionModelMediaElement> model = PlaybackSessionModelMediaElement::create();
>-    RefPtr<PlaybackSessionInterfaceContext> interface = PlaybackSessionInterfaceContext::create(*this, contextId);
>-    model->addClient(*interface);
>+    Ref<PlaybackSessionModelMediaElement> model = PlaybackSessionModelMediaElement::create();
>+    Ref<PlaybackSessionInterfaceContext> interface = PlaybackSessionInterfaceContext::create(makeWeakPtr(this), contextId);
>+    model->addClient(interface->createWeakPtr());
> 
>     return std::make_tuple(WTFMove(model), WTFMove(interface));
> }
>@@ -236,8 +231,6 @@ void PlaybackSessionManager::removeContext(uint64_t contextId)
> 
>     RefPtr<HTMLMediaElement> mediaElement = model->mediaElement();
>     model->setMediaElement(nullptr);
>-    model->removeClient(*interface);
>-    interface->invalidate();
>     m_mediaElements.remove(mediaElement.get());
>     m_contextMap.remove(contextId);
> }
>diff --git a/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.h b/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.h
>index ff8c4baf463be3539830290ecd246ef9fcfb1dfa..d5e3a8f173284b4b0eb1a3cf619bb51dbd172f4b 100644
>--- a/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.h
>+++ b/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.h
>@@ -60,9 +60,9 @@ class VideoFullscreenInterfaceContext
>     : public RefCounted<VideoFullscreenInterfaceContext>
>     , public WebCore::VideoFullscreenModelClient {
> public:
>-    static Ref<VideoFullscreenInterfaceContext> create(VideoFullscreenManager& manager, uint64_t contextId)
>+    static Ref<VideoFullscreenInterfaceContext> create(WeakPtr<VideoFullscreenManager>&& manager, uint64_t contextId)
>     {
>-        return adoptRef(*new VideoFullscreenInterfaceContext(manager, contextId));
>+        return adoptRef(*new VideoFullscreenInterfaceContext(WTFMove(manager), contextId));
>     }
>     virtual ~VideoFullscreenInterfaceContext();
> 
>@@ -86,14 +86,16 @@ public:
>     bool isFullscreen() const { return m_isFullscreen; }
>     void setIsFullscreen(bool flag) { m_isFullscreen = flag; }
> 
>+    WeakPtr<WebCore::VideoFullscreenModelClient> createWeakPtr() { return m_weakPtrFactory.createWeakPtr(*this); }
>+
> private:
>     // VideoFullscreenModelClient
>     void hasVideoChanged(bool) override;
>     void videoDimensionsChanged(const WebCore::FloatSize&) override;
> 
>-    VideoFullscreenInterfaceContext(VideoFullscreenManager&, uint64_t contextId);
>+    VideoFullscreenInterfaceContext(WeakPtr<VideoFullscreenManager>&&, uint64_t contextId);
> 
>-    VideoFullscreenManager* m_manager;
>+    WeakPtr<VideoFullscreenManager> m_manager;
>     uint64_t m_contextId;
>     std::unique_ptr<LayerHostingContext> m_layerHostingContext;
>     bool m_isAnimating { false };
>@@ -101,9 +103,13 @@ private:
>     WebCore::HTMLMediaElementEnums::VideoFullscreenMode m_fullscreenMode { WebCore::HTMLMediaElementEnums::VideoFullscreenModeNone };
>     bool m_fullscreenStandby { false };
>     bool m_isFullscreen { false };
>+    WeakPtrFactory<WebCore::VideoFullscreenModelClient> m_weakPtrFactory;
> };
> 
>-class VideoFullscreenManager : public RefCounted<VideoFullscreenManager>, private IPC::MessageReceiver {
>+class VideoFullscreenManager
>+    : public RefCounted<VideoFullscreenManager>
>+    , public CanMakeWeakPtr<VideoFullscreenManager>
>+    , private IPC::MessageReceiver {
> public:
>     static Ref<VideoFullscreenManager> create(WebPage&, PlaybackSessionManager&);
>     virtual ~VideoFullscreenManager();
>diff --git a/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.mm b/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.mm
>index f9fd6afea18ec398d1fc740a58de0af2ca2a3289..70f4d3a8a8ebaba8964d28a22401e10fa3eb0b4b 100644
>--- a/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.mm
>+++ b/Source/WebKit/WebProcess/cocoa/VideoFullscreenManager.mm
>@@ -81,8 +81,8 @@ static IntRect inlineVideoFrame(HTMLVideoElement& element)
> 
> #pragma mark - VideoFullscreenInterfaceContext
> 
>-VideoFullscreenInterfaceContext::VideoFullscreenInterfaceContext(VideoFullscreenManager& manager, uint64_t contextId)
>-    : m_manager(&manager)
>+VideoFullscreenInterfaceContext::VideoFullscreenInterfaceContext(WeakPtr<VideoFullscreenManager>&& manager, uint64_t contextId)
>+    : m_manager(WTFMove(manager))
>     , m_contextId(contextId)
> {
> }
>@@ -130,9 +130,6 @@ VideoFullscreenManager::~VideoFullscreenManager()
>         std::tie(model, interface) = tuple;
> 
>         model->setVideoElement(nullptr);
>-        model->removeClient(*interface);
>-
>-        interface->invalidate();
>     }
> 
>     m_contextMap.clear();
>@@ -153,11 +150,11 @@ void VideoFullscreenManager::invalidate()
> VideoFullscreenManager::ModelInterfaceTuple VideoFullscreenManager::createModelAndInterface(uint64_t contextId)
> {
>     RefPtr<VideoFullscreenModelVideoElement> model = VideoFullscreenModelVideoElement::create();
>-    RefPtr<VideoFullscreenInterfaceContext> interface = VideoFullscreenInterfaceContext::create(*this, contextId);
>+    RefPtr<VideoFullscreenInterfaceContext> interface = VideoFullscreenInterfaceContext::create(makeWeakPtr(*this), contextId);
>     m_playbackSessionManager->addClientForContext(contextId);
> 
>     interface->setLayerHostingContext(LayerHostingContext::createForExternalHostingProcess());
>-    model->addClient(*interface);
>+    model->addClient(interface->createWeakPtr());
> 
>     return std::make_tuple(WTFMove(model), WTFMove(interface));
> }
>@@ -190,8 +187,6 @@ void VideoFullscreenManager::removeContext(uint64_t contextId)
> 
>     RefPtr<HTMLVideoElement> videoElement = model->videoElement();
>     model->setVideoElement(nullptr);
>-    model->removeClient(*interface);
>-    interface->invalidate();
>     m_videoElements.remove(videoElement.get());
>     m_contextMap.remove(contextId);
> }

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Attachments on bug 188747: 347511 | 347515 | 347526 | 347531 | 347533 | 347537 | 347841 | 347847 | 347870 | 347922 | 349452 | 349486 | 349491 | 349784 | 349795 | 349838 | 351008 | 351130