Attachment 361953 Details for Bug 194594 – Patch

[patch] Patch

bug-194594-20190213160615.patch (text/plain), 106.38 KB, created by Chris Dumez on 2019-02-13 16:06:16 PST

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Creator: Chris Dumez

Created: 2019-02-13 16:06:16 PST

Size: 106.38 KB

patch

obsolete

>Subversion Revision: 241482
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index d99f481d12083ffdb9202410c339b26d8d1dbc64..3feab5de788da31f784c09d4401b6dd645172d23 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,15 @@
>+2019-02-13  Chris Dumez  <cdumez@apple.com>
>+
>+        [PSON] Introduce a WebContent Process cache
>+        https://bugs.webkit.org/show_bug.cgi?id=194594
>+        <rdar://problem/46793397>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Update localizable strings.
>+
>+        * en.lproj/Localizable.strings:
>+
> 2019-02-13  Chris Dumez  <cdumez@apple.com>
> 
>         Unreviewed, update localizable strings.
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index c73fd7ef3adba282dafc68dd38f02e17bf841b25..d49abbfd8367355fd76ab32b3ae45e9359430d27 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,186 @@
>+2019-02-13  Chris Dumez  <cdumez@apple.com>
>+
>+        [PSON] Introduce a WebContent Process cache
>+        https://bugs.webkit.org/show_bug.cgi?id=194594
>+        <rdar://problem/46793397>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Introduce a WebContent Process cache to reduce the number of process launches when
>+        process swap on navigation is enabled, and to reduce the power cost of the feature.
>+
>+        If a WebProcess loaded pages from a single registrable domain then it is eligible
>+        for the cache. When process-swapping on navigation to a new registrable domain, we
>+        now attempt to retrieve a process from the cache for the domain in question instead
>+        of always launching a new one.
>+
>+        The WebProcess cache currently has the following attributes:
>+        - It may contains 4 processes per GB of RAM the machine has, up to 30 processes.
>+        - WebProcesses automatically get evicted from the cache after 30 minutes.
>+        - If the application is no longer the active app, then the cache will get cleared
>+          after 5 minutes.
>+        - WebProcesses that are in the cache are reported as "(Cached)" in Activity Monitor.
>+
>+        The WebProcess cache is currently disabled by default and can by enabled by the
>+        client via SPI.
>+
>+        * Shared/WebBackForwardListItem.cpp:
>+        (WebKit::WebBackForwardListItem::WebBackForwardListItem):
>+        * Shared/WebBackForwardListItem.h:
>+        (WebKit::WebBackForwardListItem::lastProcessIdentifier const):
>+        (WebKit::WebBackForwardListItem::setLastProcessIdentifier):
>+        Add new lastProcessIdentifier data member that reflects which process this item
>+        was last loaded in. It is normally identical to the identifier of the process
>+        that created the item but it gets overriden in case of cross-site client-side
>+        redirect, since a new process takes over the item in this case.
>+
>+        * Sources.txt:
>+        Add new source file.
>+
>+        * UIProcess/API/APIProcessPoolConfiguration.cpp:
>+        (API::ProcessPoolConfiguration::copy):
>+        * UIProcess/API/APIProcessPoolConfiguration.h:
>+        * UIProcess/API/C/WKContextConfigurationRef.cpp:
>+        (WKContextConfigurationUsesWebProcessCache):
>+        (WKContextConfigurationSetUsesWebProcessCache):
>+        * UIProcess/API/C/WKContextConfigurationRef.h:
>+        * UIProcess/API/Cocoa/_WKProcessPoolConfiguration.h:
>+        * UIProcess/API/Cocoa/_WKProcessPoolConfiguration.mm:
>+        (-[_WKProcessPoolConfiguration setUsesWebProcessCache:]):
>+        (-[_WKProcessPoolConfiguration usesWebProcessCache]):
>+        Add new SPI to enable the WebProcess cache.
>+
>+        * UIProcess/API/Cocoa/WKProcessPool.mm:
>+        (-[WKProcessPool _webProcessCountIgnoringPrewarmedAndCached]):
>+        * UIProcess/API/Cocoa/WKProcessPoolPrivate.h:
>+        Add new SPI for testing which returns the number of WebProcesses ignoring
>+        both prewarmed and cached ones.
>+
>+        * UIProcess/Cocoa/WebProcessPoolCocoa.mm:
>+        (WebKit::WebProcessPool::registerNotificationObservers):
>+        (WebKit::WebProcessPool::unregisterNotificationObservers):
>+        Add application active state observers as the WebProcess cache gets cleared
>+        when the application resigns active state for more than 5 minutes.
>+
>+        * UIProcess/ProvisionalPageProxy.cpp:
>+        (WebKit::ProvisionalPageProxy::loadRequest):
>+        When doing a load in a new process with the BackForwardList locked (i.e. client-side
>+        redirect), make sure we update the last process identifier for the BackForwardListItem.
>+        This is important because the logic in WebProcessPool::processForNavigation() relies on
>+        this identifier to select which process to do the history navigation into, and we want
>+        to do the load in the post-redirect process, not the pre-redirect one.
>+
>+        * UIProcess/WebPageProxy.cpp:
>+        (WebKit::WebPageProxy::didStartProvisionalLoadForFrameShared):
>+        Tell the WebProcess whenever a main frame provisional load is started, providing the URL.
>+
>+        * UIProcess/WebProcessCache.cpp: Added.
>+        (WebKit::WebProcessCache::WebProcessCache):
>+        (WebKit::WebProcessCache::addProcess):
>+        (WebKit::WebProcessCache::takeProcess):
>+        (WebKit::WebProcessCache::updateMaximumSize):
>+        (WebKit::WebProcessCache::clear):
>+        (WebKit::WebProcessCache::setApplicationIsActive):
>+        (WebKit::WebProcessCache::evictProcess):
>+        (WebKit::WebProcessCache::CachedProcess::CachedProcess):
>+        (WebKit::WebProcessCache::CachedProcess::~CachedProcess):
>+        (WebKit::WebProcessCache::CachedProcess::takeProcess):
>+        (WebKit::WebProcessCache::CachedProcess::evictionTimerFired):
>+        * UIProcess/WebProcessCache.h: Added.
>+        (WebKit::WebProcessCache::maximumSize):
>+        (WebKit::WebProcessCache::size const):
>+        (WebKit::WebProcessCache::CachedProcess::process):
>+        Add process cache implementation.
>+
>+        * UIProcess/WebProcessPool.cpp:
>+        (WebKit::m_webProcessCache):
>+        WebProcessCache is stored on the WebProcessPool via m_webProcessCache data member.
>+
>+        (WebKit::WebProcessPool::~WebProcessPool):
>+        Clear the WebProcess cache in the destructor.
>+
>+        (WebKit::WebProcessPool::setApplicationIsActive):
>+        Notify the WebProcessCache whenever the application's active state changes.
>+
>+        (WebKit::WebProcessPool::createWebPage):
>+        If the state of PSON changes via the experimental features menu, dynamically
>+        update the WebProcessCache's size. This is needed because the cache is disabled
>+        when PSON is disabled.
>+
>+        (WebKit::WebProcessPool::handleMemoryPressureWarning):
>+        Clear the WebProcess cache on memory pressure.
>+
>+        (WebKit::WebProcessPool::processForNavigationInternal):
>+        Query the WebProcessCache before attempting to create a new WebProcess for a cross-site
>+        navigation.
>+
>+        (WebKit::WebProcessPool::findReusableSuspendedPageProcess):
>+        This logic was split out of processForNavigationInternal() to reduce the size
>+        of the method.
>+
>+        * UIProcess/WebProcessPool.h:
>+        * UIProcess/WebProcessProxy.cpp:
>+        (WebKit::WebProcessProxy::setIsInProcessCache):
>+        Update the isInProcessCache flag on the WebProcessProxy and send an IPC to the WebContent
>+        process so that it can update its name in Activity Monitor.
>+        We also need to stop holding a strong reference to the WebProcessPool whenever the process
>+        is in the cache, similarly to what we do for pre-warmed processes, given that such processes
>+        should not keep the process pool alive.
>+
>+        (WebKit::WebProcessProxy::addExistingWebPage):
>+        Assert that we never try to add a page to a cached process, it should be taken out of the
>+        cache before use.
>+
>+        (WebKit::WebProcessProxy::hasProvisionalPageWithID const):
>+        (WebKit::WebProcessProxy::isAllowedToUpdateBackForwardItem const):
>+        (WebKit::WebProcessProxy::updateBackForwardItem):
>+        In case of client-side redirects, the previous process would sometimes send an IPC causing
>+        the UIProcess' backforward list item to get updated with the pre-redirect URL after we've
>+        already redirected. This previously would be unlikely to occur because we do not suspend
>+        client-redirect pages and their process would normally exit before getting a chance to send
>+        the IPC. However, with the process cache, the bug became obvious as the process would stay
>+        alive and send up the "bad" IPC. To address the issue, we now only let the IPC update the
>+        item if the item's page is (still) associated with the process. In the future, we may want
>+        to update the IPC so that it gets sent to the WebPageProxy instead of the WebProcessProxy.
>+
>+        (WebKit::WebProcessProxy::processDidTerminateOrFailedToLaunch):
>+        If a cached WebProcess crashes, remove it from the cache so that we do not attempt to use
>+        it for a load later.
>+
>+        (WebKit::WebProcessProxy::canBeAddedToWebProcessCache const):
>+        Only cache WebProcesses that have loaded a single registrable domain. Also prevent caching
>+        for service worker and inspector processes.
>+
>+        (WebKit::WebProcessProxy::maybeShutDown):
>+        If the process is cacheable, add it to the cache instead of shutting it down right away.
>+
>+        (WebKit::WebProcessProxy::canTerminateAuxiliaryProcess):
>+        Make sure we do not attempt to terminate a processes that is in the cache.
>+
>+        (WebKit::WebProcessProxy::didStartProvisionalLoadForMainFrame):
>+        Whenever a main frame provisional load starts, make sure we update the process's associated
>+        registrable domain. nullopt indicates that there is no associated domain yet. Null string
>+        indicates that the process is associated with several registrable domain and is therefore
>+        not eligible for caching.
>+
>+        * UIProcess/WebProcessProxy.h:
>+        (WebKit::WebProcessProxy::registrableDomain const):
>+        (WebKit::WebProcessProxy::isInProcessCache const):
>+        (WebKit::WebProcessProxy::provisionalPageCount const):
>+        Add convenience getters.
>+
>+        * WebKit.xcodeproj/project.pbxproj:
>+        Add new files to project.
>+
>+        * WebProcess/WebProcess.cpp:
>+        (WebKit::WebProcess::setIsInProcessCache):
>+        * WebProcess/WebProcess.h:
>+        * WebProcess/WebProcess.messages.in:
>+        * WebProcess/cocoa/WebProcessCocoa.mm:
>+        (WebKit::WebProcess::updateProcessName):
>+        Update the WebProcess' name in Activity Monitor whenever it goes into or out of the WebProcess
>+        cache.
>+
> 2019-02-13  Tim Horton  <timothy_horton@apple.com>
> 
>         Encrypted PDFs inside <embed> or <object> crash the Web Content process
>diff --git a/Source/WebCore/en.lproj/Localizable.strings b/Source/WebCore/en.lproj/Localizable.strings
>index fbe299ee2a24a23b753b12607ced256d0ed1c0ea..f144191835c390c21de5bdf1c965b6b1a95ac059 100644
>--- a/Source/WebCore/en.lproj/Localizable.strings
>+++ b/Source/WebCore/en.lproj/Localizable.strings
>@@ -46,6 +46,9 @@
> /* Visible name of the web process. The argument is the application name. */
> "%@ Web Content" = "%@ Web Content";
> 
>+/* Visible name of the web process. The argument is the application name. */
>+"%@ Web Content (Cached)" = "%@ Web Content (Cached)";
>+
> /* Visible name of the web process. The argument is the application name. */
> "%@ Web Content (Prewarmed)" = "%@ Web Content (Prewarmed)";
> 
>diff --git a/Source/WebKit/Shared/WebBackForwardListItem.cpp b/Source/WebKit/Shared/WebBackForwardListItem.cpp
>index 03b43f1c97b1eb87ddc0f44153ec828f5ce44498..9dbb36a45536aa373bc97d0a7cf4d842dff396ed 100644
>--- a/Source/WebKit/Shared/WebBackForwardListItem.cpp
>+++ b/Source/WebKit/Shared/WebBackForwardListItem.cpp
>@@ -43,6 +43,7 @@ Ref<WebBackForwardListItem> WebBackForwardListItem::create(BackForwardListItemSt
> WebBackForwardListItem::WebBackForwardListItem(BackForwardListItemState&& backForwardListItemState, uint64_t pageID)
>     : m_itemState(WTFMove(backForwardListItemState))
>     , m_pageID(pageID)
>+    , m_lastProcessIdentifier(m_itemState.identifier.processIdentifier)
> {
>     auto result = allItems().add(m_itemState.identifier, this);
>     ASSERT_UNUSED(result, result.isNewEntry);
>diff --git a/Source/WebKit/Shared/WebBackForwardListItem.h b/Source/WebKit/Shared/WebBackForwardListItem.h
>index bff0c882041f6a9aa8332166fd7b377ec3f1b583..872ef18095d18cc3a9c5e7463d30e7f614872f5e 100644
>--- a/Source/WebKit/Shared/WebBackForwardListItem.h
>+++ b/Source/WebKit/Shared/WebBackForwardListItem.h
>@@ -56,6 +56,9 @@ public:
>     const BackForwardListItemState& itemState() { return m_itemState; }
>     uint64_t pageID() const { return m_pageID; }
> 
>+    WebCore::ProcessIdentifier lastProcessIdentifier() const { return m_lastProcessIdentifier; }
>+    void setLastProcessIdentifier(const WebCore::ProcessIdentifier& identifier) { m_lastProcessIdentifier = identifier; }
>+
>     void setPageState(PageState pageState) { m_itemState.pageState = WTFMove(pageState); }
>     const PageState& pageState() const { return m_itemState.pageState; }
> 
>@@ -84,6 +87,7 @@ private:
> 
>     BackForwardListItemState m_itemState;
>     uint64_t m_pageID;
>+    WebCore::ProcessIdentifier m_lastProcessIdentifier;
>     WeakPtr<SuspendedPageProxy> m_suspendedPage;
> };
> 
>diff --git a/Source/WebKit/Sources.txt b/Source/WebKit/Sources.txt
>index 6673f3df8175b47e4d5d704596109dab5c23685f..59cef83a5239eea0ca197f68cb372067b979e029 100644
>--- a/Source/WebKit/Sources.txt
>+++ b/Source/WebKit/Sources.txt
>@@ -277,6 +277,7 @@ UIProcess/WebPageInspectorTargetAgent.cpp
> UIProcess/WebPageProxy.cpp
> UIProcess/WebPasteboardProxy.cpp
> UIProcess/WebPreferences.cpp
>+UIProcess/WebProcessCache.cpp
> UIProcess/WebProcessLifetimeObserver.cpp
> UIProcess/WebProcessLifetimeTracker.cpp
> UIProcess/WebProcessPool.cpp
>diff --git a/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.cpp b/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.cpp
>index d17978e5e64110108f8f120f6df0ddcc12b78483..23cf03519895b9d38c42bb09944b45725a6659f3 100644
>--- a/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.cpp
>+++ b/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.cpp
>@@ -124,6 +124,7 @@ Ref<ProcessPoolConfiguration> ProcessPoolConfiguration::copy()
>     copy->m_alwaysKeepAndReuseSwappedProcesses = this->m_alwaysKeepAndReuseSwappedProcesses;
>     copy->m_processSwapsOnWindowOpenWithOpener = this->m_processSwapsOnWindowOpenWithOpener;
>     copy->m_isAutomaticProcessWarmingEnabledByClient = this->m_isAutomaticProcessWarmingEnabledByClient;
>+    copy->m_usesWebProcessCache = this->m_usesWebProcessCache;
> #if ENABLE(PROXIMITY_NETWORKING)
>     copy->m_wirelessContextIdentifier = this->m_wirelessContextIdentifier;
> #endif
>diff --git a/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.h b/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.h
>index e3a6a772569b68308a5730006bc19837e9bd4608..a016612c69c737e280d2880bcb112f69be87ae64 100644
>--- a/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.h
>+++ b/Source/WebKit/UIProcess/API/APIProcessPoolConfiguration.h
>@@ -67,6 +67,9 @@ public:
>     bool wasAutomaticProcessWarmingSetByClient() const { return !!m_isAutomaticProcessWarmingEnabledByClient; }
>     void setIsAutomaticProcessWarmingEnabled(bool value) { m_isAutomaticProcessWarmingEnabledByClient = value; }
> 
>+    void setUsesWebProcessCache(bool value) { m_usesWebProcessCache = value; }
>+    bool usesWebProcessCache() const { return m_usesWebProcessCache; }
>+
>     bool clientWouldBenefitFromAutomaticProcessPrewarming() const { return m_clientWouldBenefitFromAutomaticProcessPrewarming; }
>     void setClientWouldBenefitFromAutomaticProcessPrewarming(bool value) { m_clientWouldBenefitFromAutomaticProcessPrewarming = value; }
> 
>@@ -223,6 +226,7 @@ private:
>     bool m_alwaysKeepAndReuseSwappedProcesses { false };
>     bool m_processSwapsOnWindowOpenWithOpener { false };
>     Optional<bool> m_isAutomaticProcessWarmingEnabledByClient;
>+    bool m_usesWebProcessCache { false };
>     bool m_clientWouldBenefitFromAutomaticProcessPrewarming { false };
>     WTF::String m_customWebContentServiceBundleIdentifier;
>     bool m_isJITEnabled { true };
>diff --git a/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.cpp b/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.cpp
>index 338c0ddd7696c32d5d5c0ae1da865bf325c1b37e..17653142df67f4f3bee29125465e418de6687279 100644
>--- a/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.cpp
>+++ b/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.cpp
>@@ -188,6 +188,16 @@ void WKContextConfigurationSetPrewarmsProcessesAutomatically(WKContextConfigurat
>     toImpl(configuration)->setIsAutomaticProcessWarmingEnabled(prewarms);
> }
> 
>+bool WKContextConfigurationUsesWebProcessCache(WKContextConfigurationRef configuration)
>+{
>+    return toImpl(configuration)->usesWebProcessCache();
>+}
>+
>+void WKContextConfigurationSetUsesWebProcessCache(WKContextConfigurationRef configuration, bool uses)
>+{
>+    toImpl(configuration)->setUsesWebProcessCache(uses);
>+}
>+
> bool WKContextConfigurationAlwaysKeepAndReuseSwappedProcesses(WKContextConfigurationRef configuration)
> {
>     return toImpl(configuration)->alwaysKeepAndReuseSwappedProcesses();
>diff --git a/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.h b/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.h
>index ad3e7a172f80354eca982403a49fa885142fe575..93985ad837fca96c3c8b3fd9d658289c867b26a0 100644
>--- a/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.h
>+++ b/Source/WebKit/UIProcess/API/C/WKContextConfigurationRef.h
>@@ -78,6 +78,9 @@ WK_EXPORT void WKContextConfigurationSetProcessSwapsOnNavigation(WKContextConfig
> WK_EXPORT bool WKContextConfigurationPrewarmsProcessesAutomatically(WKContextConfigurationRef configuration);
> WK_EXPORT void WKContextConfigurationSetPrewarmsProcessesAutomatically(WKContextConfigurationRef configuration, bool prewarms);
> 
>+WK_EXPORT bool WKContextConfigurationUsesWebProcessCache(WKContextConfigurationRef configuration);
>+WK_EXPORT void WKContextConfigurationSetUsesWebProcessCache(WKContextConfigurationRef configuration, bool uses);
>+
> WK_EXPORT bool WKContextConfigurationAlwaysKeepAndReuseSwappedProcesses(WKContextConfigurationRef configuration);
> WK_EXPORT void WKContextConfigurationSetAlwaysKeepAndReuseSwappedProcesses(WKContextConfigurationRef configuration, bool keepAndReuse);
> 
>diff --git a/Source/WebKit/UIProcess/API/Cocoa/WKProcessPool.mm b/Source/WebKit/UIProcess/API/Cocoa/WKProcessPool.mm
>index 298b44e2f18f868d7941894d2da793abddd16261..c345cd9832d5c9ba18c15be7ee45c0a13685e51e 100644
>--- a/Source/WebKit/UIProcess/API/Cocoa/WKProcessPool.mm
>+++ b/Source/WebKit/UIProcess/API/Cocoa/WKProcessPool.mm
>@@ -39,6 +39,7 @@
> #import "WKWebViewInternal.h"
> #import "WebCertificateInfo.h"
> #import "WebCookieManagerProxy.h"
>+#import "WebProcessCache.h"
> #import "WebProcessMessages.h"
> #import "WebProcessPool.h"
> #import "_WKAutomationDelegate.h"
>@@ -475,6 +476,11 @@ - (size_t)_webProcessCountIgnoringPrewarmed
>     return [self _webProcessCount] - ([self _hasPrewarmedWebProcess] ? 1 : 0);
> }
> 
>+- (size_t)_webProcessCountIgnoringPrewarmedAndCached
>+{
>+    return [self _webProcessCount] - ([self _hasPrewarmedWebProcess] ? 1 : 0) - _processPool->webProcessCache().size();
>+}
>+
> - (size_t)_webPageContentProcessCount
> {
>     auto allWebProcesses = _processPool->processes();
>diff --git a/Source/WebKit/UIProcess/API/Cocoa/WKProcessPoolPrivate.h b/Source/WebKit/UIProcess/API/Cocoa/WKProcessPoolPrivate.h
>index 470dd5394a21407046ae2bae5387b6658eb2cb6e..075f7197e97ccca9a475ea8486846ee17226c893 100644
>--- a/Source/WebKit/UIProcess/API/Cocoa/WKProcessPoolPrivate.h
>+++ b/Source/WebKit/UIProcess/API/Cocoa/WKProcessPoolPrivate.h
>@@ -96,6 +96,7 @@
> - (size_t)_webProcessCount WK_API_AVAILABLE(macosx(10.13), ios(11.0));
> - (BOOL)_hasPrewarmedWebProcess WK_API_AVAILABLE(macosx(WK_MAC_TBA), ios(WK_IOS_TBA));
> - (size_t)_webProcessCountIgnoringPrewarmed WK_API_AVAILABLE(macosx(10.14), ios(12.0));
>+- (size_t)_webProcessCountIgnoringPrewarmedAndCached WK_API_AVAILABLE(macosx(WK_MAC_TBA), ios(WK_IOS_TBA));
> - (size_t)_pluginProcessCount WK_API_AVAILABLE(macosx(10.13.4), ios(11.3));
> - (size_t)_serviceWorkerProcessCount WK_API_AVAILABLE(macosx(10.14), ios(12.0));
> - (void)_syncNetworkProcessCookies WK_API_AVAILABLE(macosx(10.13), ios(11.0));
>diff --git a/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.h b/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.h
>index f671d7b4c2b8bf986b6e4a50ce090951728ca43d..40500d96a2de4dd21191ad8373d1ea6cc3e1b796 100644
>--- a/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.h
>+++ b/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.h
>@@ -67,6 +67,7 @@ WK_CLASS_AVAILABLE(macosx(10.10), ios(8.0))
> @property (nonatomic) BOOL alwaysKeepAndReuseSwappedProcesses WK_API_AVAILABLE(macosx(10.14), ios(12.0));
> @property (nonatomic) BOOL processSwapsOnWindowOpenWithOpener WK_API_AVAILABLE(macosx(10.14), ios(12.0));
> @property (nonatomic) BOOL prewarmsProcessesAutomatically WK_API_AVAILABLE(macosx(WK_MAC_TBA), ios(WK_IOS_TBA));
>+@property (nonatomic) BOOL usesWebProcessCache WK_API_AVAILABLE(macosx(WK_MAC_TBA), ios(WK_IOS_TBA));
> @property (nonatomic) BOOL pageCacheEnabled WK_API_AVAILABLE(macosx(10.14), ios(12.0));
> @property (nonatomic) BOOL suppressesConnectionTerminationOnSystemChange WK_API_AVAILABLE(macosx(10.14), ios(12.0));
> @property (nonatomic, getter=isJITEnabled) BOOL JITEnabled WK_API_AVAILABLE(macosx(WK_MAC_TBA), ios(WK_IOS_TBA));
>diff --git a/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.mm b/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.mm
>index 8a36781988ee07c2e70589fbfb357e0f11a0ea32..01bf6a545d8fd77629ed4402094650b8effb45c0 100644
>--- a/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.mm
>+++ b/Source/WebKit/UIProcess/API/Cocoa/_WKProcessPoolConfiguration.mm
>@@ -258,6 +258,16 @@ - (BOOL)prewarmsProcessesAutomatically
>     return _processPoolConfiguration->isAutomaticProcessWarmingEnabled();
> }
> 
>+- (void)setUsesWebProcessCache:(BOOL)value
>+{
>+    _processPoolConfiguration->setUsesWebProcessCache(value);
>+}
>+
>+- (BOOL)usesWebProcessCache
>+{
>+    return _processPoolConfiguration->usesWebProcessCache();
>+}
>+
> - (void)setAlwaysKeepAndReuseSwappedProcesses:(BOOL)swaps
> {
>     _processPoolConfiguration->setAlwaysKeepAndReuseSwappedProcesses(swaps);
>diff --git a/Source/WebKit/UIProcess/Cocoa/WebProcessPoolCocoa.mm b/Source/WebKit/UIProcess/Cocoa/WebProcessPoolCocoa.mm
>index 70c91a6a14518ee5962eaa78baa700d5fae612ca..98746c37c524c8784b7a6e826676665175f6fb0d 100644
>--- a/Source/WebKit/UIProcess/Cocoa/WebProcessPoolCocoa.mm
>+++ b/Source/WebKit/UIProcess/Cocoa/WebProcessPoolCocoa.mm
>@@ -418,6 +418,14 @@ void WebProcessPool::registerNotificationObservers()
>     }];
> #endif
> 
>+    m_activationObserver = [[NSNotificationCenter defaultCenter] addObserverForName:NSApplicationDidBecomeActiveNotification object:NSApp queue:[NSOperationQueue currentQueue] usingBlock:^(NSNotification *notification) {
>+        setApplicationIsActive(true);
>+    }];
>+
>+    m_deactivationObserver = [[NSNotificationCenter defaultCenter] addObserverForName:NSApplicationDidResignActiveNotification object:NSApp queue:[NSOperationQueue currentQueue] usingBlock:^(NSNotification *notification) {
>+        setApplicationIsActive(false);
>+    }];
>+
> #endif // !PLATFORM(IOS_FAMILY)
> }
> 
>@@ -433,6 +441,8 @@ void WebProcessPool::unregisterNotificationObservers()
> #if ENABLE(WEBPROCESS_WINDOWSERVER_BLOCKING)
>     [[NSNotificationCenter defaultCenter] removeObserver:m_scrollerStyleNotificationObserver.get()];
> #endif
>+    [[NSNotificationCenter defaultCenter] removeObserver:m_activationObserver.get()];
>+    [[NSNotificationCenter defaultCenter] removeObserver:m_deactivationObserver.get()];
> #endif // !PLATFORM(IOS_FAMILY)
> }
> 
>diff --git a/Source/WebKit/UIProcess/ProvisionalPageProxy.cpp b/Source/WebKit/UIProcess/ProvisionalPageProxy.cpp
>index a3f5711b051ee1f494e0f7ca7fbe89659f1cc434..b66ff9b4dd1d07f66aaaa4a1196f9a834df97c83 100644
>--- a/Source/WebKit/UIProcess/ProvisionalPageProxy.cpp
>+++ b/Source/WebKit/UIProcess/ProvisionalPageProxy.cpp
>@@ -154,6 +154,12 @@ void ProvisionalPageProxy::loadRequest(API::Navigation& navigation, WebCore::Res
> {
>     RELEASE_LOG_IF_ALLOWED(ProcessSwapping, "loadRequest: pageID = %" PRIu64, m_page.pageID());
> 
>+    // If this is a client-side redirect continuing in a new process, then the new process will overwrite the fromItem's URL. In this case,
>+    // we need to make sure we update fromItem's processIdentifier as we want future navigations to this BackForward item to happen in the
>+    // new process.
>+    if (navigation.fromItem() && navigation.lockBackForwardList() == WebCore::LockBackForwardList::Yes)
>+        navigation.fromItem()->setLastProcessIdentifier(m_process->coreProcessIdentifier());
>+
>     m_page.loadRequestWithNavigationShared(m_process.copyRef(), navigation, WTFMove(request), shouldOpenExternalURLsPolicy, userData, WebCore::ShouldTreatAsContinuingLoad::Yes, WTFMove(websitePolicies));
> }
> 
>diff --git a/Source/WebKit/UIProcess/WebPageProxy.cpp b/Source/WebKit/UIProcess/WebPageProxy.cpp
>index da13f2bb83161e4f3a6e09cd7c10f583dbcd05fa..174531a4345fb85bbdc8089d5fd93f7e35781ff9 100644
>--- a/Source/WebKit/UIProcess/WebPageProxy.cpp
>+++ b/Source/WebKit/UIProcess/WebPageProxy.cpp
>@@ -3834,6 +3834,7 @@ void WebPageProxy::didStartProvisionalLoadForFrameShared(Ref<WebProcessProxy>&&
>     m_pageLoadState.clearPendingAPIRequestURL(transaction);
> 
>     if (frame->isMainFrame()) {
>+        process->didStartProvisionalLoadForMainFrame(url);
>         reportPageLoadResult(ResourceError { ResourceError::Type::Cancellation });
>         m_pageLoadStart = MonotonicTime::now();
>         m_pageLoadState.didStartProvisionalLoad(transaction, url, unreachableURL);
>diff --git a/Source/WebKit/UIProcess/WebProcessCache.cpp b/Source/WebKit/UIProcess/WebProcessCache.cpp
>new file mode 100644
>index 0000000000000000000000000000000000000000..8c4a4c620cd6a45c0eb02b48ae467fd5c331a6e1
>--- /dev/null
>+++ b/Source/WebKit/UIProcess/WebProcessCache.cpp
>@@ -0,0 +1,176 @@
>+/*
>+ * Copyright (C) 2019 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.
>+ */
>+
>+#include "config.h"
>+#include "WebProcessCache.h"
>+
>+#include "Logging.h"
>+#include "WebProcessPool.h"
>+#include "WebProcessProxy.h"
>+#include <wtf/RAMSize.h>
>+#include <wtf/StdLibExtras.h>
>+
>+namespace WebKit {
>+
>+static Seconds cachedProcessLifetime { 30_min };
>+static Seconds clearingDelayAfterApplicationResignsActive { 5_min };
>+
>+WebProcessCache::WebProcessCache(WebProcessPool& processPool)
>+    : m_evictionTimer(RunLoop::main(), this, &WebProcessCache::clear)
>+{
>+    updateMaximumSize(processPool);
>+}
>+
>+bool WebProcessCache::addProcess(const String& registrableDomain, Ref<WebProcessProxy>&& process)
>+{
>+    ASSERT(!registrableDomain.isEmpty());
>+    ASSERT(!process->pageCount());
>+    ASSERT(!process->provisionalPageCount());
>+    ASSERT(!process->processPool().hasSuspendedPageFor(process));
>+
>+    if (!maximumSize())
>+        return false;
>+
>+    while (m_processesPerRegistrableDomain.size() >= maximumSize()) {
>+        auto it = m_processesPerRegistrableDomain.random();
>+        RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::addProcess(): Evicting process %i from WebProcess cache", this, it->value->process().processIdentifier());
>+        m_processesPerRegistrableDomain.remove(it);
>+    }
>+
>+    auto addResult = m_processesPerRegistrableDomain.ensure(registrableDomain, [process = process.copyRef()]() mutable {
>+        return std::make_unique<CachedProcess>(WTFMove(process));
>+    });
>+    if (!addResult.isNewEntry)
>+        return false;
>+
>+    RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::addProcess: Adding process %i to WebProcess cache, cache size: [%u / %u]", this, process->processIdentifier(), size(), maximumSize());
>+    return true;
>+}
>+
>+RefPtr<WebProcessProxy> WebProcessCache::takeProcess(const String& registrableDomain, WebsiteDataStore& dataStore)
>+{
>+    auto it = m_processesPerRegistrableDomain.find(registrableDomain);
>+    if (it == m_processesPerRegistrableDomain.end())
>+        return nullptr;
>+
>+    if (&it->value->process().websiteDataStore() != &dataStore)
>+        return nullptr;
>+
>+    auto process = it->value->takeProcess();
>+    m_processesPerRegistrableDomain.remove(it);
>+    RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::takeProcess: Taking process %i from WebProcess cache, cache size: [%u / %u]", this, process->processIdentifier(), size(), maximumSize());
>+
>+    ASSERT(!process->pageCount());
>+    ASSERT(!process->provisionalPageCount());
>+    ASSERT(!process->processPool().hasSuspendedPageFor(process));
>+
>+    return WTFMove(process);
>+}
>+
>+void WebProcessCache::updateMaximumSize(WebProcessPool& processPool)
>+{
>+    if (!processPool.configuration().processSwapsOnNavigation() || !processPool.configuration().usesWebProcessCache()) {
>+        if (!processPool.configuration().processSwapsOnNavigation())
>+            RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::updateMaximumSize: Cache is disabled because process swap on navigation is disabled", this);
>+        else
>+            RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::updateMaximumSize: Cache is disabled by client", this);
>+        m_maximumSize = 0;
>+    } else {
>+        size_t memorySize = ramSize() / GB;
>+
>+        // Allow 4 processes in the cache per GB of RAM, up to 30 processes.
>+        m_maximumSize = std::min<unsigned>(memorySize * 4, 30);
>+        RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::updateMaximumSize: Cache has a maximum size of %u processes", this, maximumSize());
>+    }
>+
>+    if (!m_maximumSize)
>+        clear();
>+}
>+
>+void WebProcessCache::clear()
>+{
>+    if (m_processesPerRegistrableDomain.isEmpty())
>+        return;
>+
>+    RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::clear() evicting %u processes", this, m_processesPerRegistrableDomain.size());
>+    m_processesPerRegistrableDomain.clear();
>+}
>+
>+void WebProcessCache::setApplicationIsActive(bool value)
>+{
>+    RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::setApplicationIsActive(%d)", this, value);
>+    if (value)
>+        m_evictionTimer.stop();
>+    else if (!m_processesPerRegistrableDomain.isEmpty())
>+        m_evictionTimer.startOneShot(clearingDelayAfterApplicationResignsActive);
>+}
>+
>+void WebProcessCache::evictProcess(WebProcessProxy& process)
>+{
>+    auto it = m_processesPerRegistrableDomain.find(process.registrableDomain());
>+    ASSERT(it != m_processesPerRegistrableDomain.end());
>+    ASSERT(&it->value->process() == &process);
>+
>+    RELEASE_LOG(ProcessSwapping, "%p - WebProcessCache::evictProcess(): Evicting process %i from WebProcess cache because it expired", this, process.processIdentifier());
>+
>+    m_processesPerRegistrableDomain.remove(it);
>+}
>+
>+WebProcessCache::CachedProcess::CachedProcess(Ref<WebProcessProxy>&& process)
>+    : m_process(WTFMove(process))
>+    , m_evictionTimer(RunLoop::main(), this, &CachedProcess::evictionTimerFired)
>+{
>+    m_process->setIsInProcessCache(true);
>+    m_evictionTimer.startOneShot(cachedProcessLifetime);
>+}
>+
>+WebProcessCache::CachedProcess::~CachedProcess()
>+{
>+    if (!m_process)
>+        return;
>+
>+    ASSERT(!m_process->pageCount());
>+    ASSERT(!m_process->provisionalPageCount());
>+    ASSERT(!m_process->processPool().hasSuspendedPageFor(*m_process));
>+
>+    m_process->setIsInProcessCache(false);
>+    m_process->shutDown();
>+}
>+
>+Ref<WebProcessProxy> WebProcessCache::CachedProcess::takeProcess()
>+{
>+    ASSERT(m_process);
>+    m_evictionTimer.stop();
>+    m_process->setIsInProcessCache(false);
>+    return m_process.releaseNonNull();
>+}
>+
>+void WebProcessCache::CachedProcess::evictionTimerFired()
>+{
>+    ASSERT(m_process);
>+    m_process->processPool().webProcessCache().evictProcess(*m_process);
>+}
>+
>+} // namespace WebKit
>diff --git a/Source/WebKit/UIProcess/WebProcessCache.h b/Source/WebKit/UIProcess/WebProcessCache.h
>new file mode 100644
>index 0000000000000000000000000000000000000000..992a1651a798447805615b9242adfe45447e22ad
>--- /dev/null
>+++ b/Source/WebKit/UIProcess/WebProcessCache.h
>@@ -0,0 +1,80 @@
>+/*
>+ * Copyright (C) 2019 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/HashMap.h>
>+#include <wtf/RunLoop.h>
>+#include <wtf/text/WTFString.h>
>+
>+namespace WebKit {
>+
>+class WebProcessPool;
>+class WebProcessProxy;
>+class WebsiteDataStore;
>+
>+class WebProcessCache {
>+    WTF_MAKE_FAST_ALLOCATED;
>+public:
>+    explicit WebProcessCache(WebProcessPool&);
>+
>+    bool addProcess(const String& registrableDomain, Ref<WebProcessProxy>&&);
>+    RefPtr<WebProcessProxy> takeProcess(const String& registrableDomain, WebsiteDataStore&);
>+
>+    void updateMaximumSize(WebProcessPool&);
>+    unsigned maximumSize() { return m_maximumSize; }
>+
>+    unsigned size() const { return m_processesPerRegistrableDomain.size(); }
>+
>+    void clear();
>+    void setApplicationIsActive(bool);
>+
>+private:
>+    void evictProcess(WebProcessProxy&);
>+
>+    unsigned m_maximumSize { 0 };
>+
>+    class CachedProcess {
>+        WTF_MAKE_FAST_ALLOCATED;
>+    public:
>+        CachedProcess(Ref<WebProcessProxy>&&);
>+        ~CachedProcess();
>+
>+        Ref<WebProcessProxy> takeProcess();
>+        WebProcessProxy& process() { ASSERT(m_process); return *m_process; }
>+
>+    private:
>+        void evictionTimerFired();
>+
>+        RefPtr<WebProcessProxy> m_process;
>+        RunLoop::Timer<CachedProcess> m_evictionTimer;
>+    };
>+
>+    HashMap<String, std::unique_ptr<CachedProcess>> m_processesPerRegistrableDomain;
>+    RunLoop::Timer<WebProcessCache> m_evictionTimer;
>+};
>+
>+} // namespace WebKit
>diff --git a/Source/WebKit/UIProcess/WebProcessPool.cpp b/Source/WebKit/UIProcess/WebProcessPool.cpp
>index c9de7fb541b00a5a30928ae4999de6b5a55c8405..eb7d380cf06fe4c70c3850b892deba464a75fa02 100644
>--- a/Source/WebKit/UIProcess/WebProcessPool.cpp
>+++ b/Source/WebKit/UIProcess/WebProcessPool.cpp
>@@ -69,6 +69,7 @@
> #include "WebPageGroup.h"
> #include "WebPreferences.h"
> #include "WebPreferencesKeys.h"
>+#include "WebProcessCache.h"
> #include "WebProcessCreationParameters.h"
> #include "WebProcessMessages.h"
> #include "WebProcessPoolMessages.h"
>@@ -255,6 +256,7 @@ WebProcessPool::WebProcessPool(API::ProcessPoolConfiguration& configuration)
>     , m_foregroundWebProcessCounter([this](RefCounterEvent) { updateProcessAssertions(); })
>     , m_backgroundWebProcessCounter([this](RefCounterEvent) { updateProcessAssertions(); })
> #endif
>+    , m_webProcessCache(makeUniqueRef<WebProcessCache>(*this))
> {
>     static std::once_flag onceFlag;
>     std::call_once(onceFlag, [] {
>@@ -313,6 +315,8 @@ WebProcessPool::WebProcessPool(API::ProcessPoolConfiguration& configuration)
> 
> WebProcessPool::~WebProcessPool()
> {
>+    m_webProcessCache->clear();
>+
>     bool removed = processPools().removeFirst(this);
>     ASSERT_UNUSED(removed, removed);
> 
>@@ -455,6 +459,11 @@ void WebProcessPool::textCheckerStateChanged()
>     sendToAllProcesses(Messages::WebProcess::SetTextCheckerState(TextChecker::state()));
> }
> 
>+void WebProcessPool::setApplicationIsActive(bool isActive)
>+{
>+    m_webProcessCache->setApplicationIsActive(isActive);
>+}
>+
> void WebProcessPool::screenPropertiesStateChanged()
> {
> #if PLATFORM(MAC)
>@@ -1154,7 +1163,11 @@ Ref<WebPageProxy> WebProcessPool::createWebPage(PageClient& pageClient, Ref<API:
>         enableProcessSwapOnCrossSiteNavigation = false;
> #endif
> 
>+    bool wasProcessSwappingOnNavigationEnabled = m_configuration->processSwapsOnNavigation();
>     m_configuration->setProcessSwapsOnNavigationFromExperimentalFeatures(enableProcessSwapOnCrossSiteNavigation);
>+    if (wasProcessSwappingOnNavigationEnabled != m_configuration->processSwapsOnNavigation())
>+        m_webProcessCache->updateMaximumSize(*this);
>+
>     m_configuration->setShouldCaptureAudioInUIProcess(page->preferences().captureAudioInUIProcessEnabled());
>     m_configuration->setShouldCaptureVideoInUIProcess(page->preferences().captureVideoInUIProcessEnabled());
> 
>@@ -1319,6 +1332,10 @@ WebProcessPool::Statistics& WebProcessPool::statistics()
> 
> void WebProcessPool::handleMemoryPressureWarning(Critical)
> {
>+    RELEASE_LOG(PerformanceLogging, "%p - WebProcessPool::handleMemoryPressureWarning", this);
>+
>+    m_webProcessCache->clear();
>+
>     if (m_prewarmedProcess)
>         m_prewarmedProcess->shutDown();
>     ASSERT(!m_prewarmedProcess);
>@@ -2153,14 +2170,24 @@ void WebProcessPool::processForNavigation(WebPageProxy& page, const API::Navigat
> void WebProcessPool::processForNavigationInternal(WebPageProxy& page, const API::Navigation& navigation, ProcessSwapRequestedByClient processSwapRequestedByClient, CompletionHandler<void(Ref<WebProcessProxy>&&, SuspendedPageProxy*, const String&)>&& completionHandler)
> {
>     auto& targetURL = navigation.currentRequest().url();
>+    auto registrableDomain = toRegistrableDomain(targetURL);
>+
>+    auto createNewProcess = [this, protectedThis = makeRef(*this), page = makeRef(page), targetURL, registrableDomain] () -> Ref<WebProcessProxy> {
>+        if (auto process = webProcessCache().takeProcess(registrableDomain, page->websiteDataStore()))
>+            return process.releaseNonNull();
>+
>+        // Check if we have a suspended page for the given registrable domain and use its process if we do, for performance reasons.
>+        if (auto process = findReusableSuspendedPageProcess(registrableDomain, page)) {
>+            RELEASE_LOG(ProcessSwapping, "Using WebProcess %i from a SuspendedPage", process->processIdentifier());
>+            return process.releaseNonNull();
>+        }
> 
>-    auto createNewProcess = [&] () -> Ref<WebProcessProxy> {
>-        if (RefPtr<WebProcessProxy> process = tryTakePrewarmedProcess(page.websiteDataStore())) {
>+        if (auto process = tryTakePrewarmedProcess(page->websiteDataStore())) {
>             tryPrewarmWithDomainInformation(*process, targetURL);
>             return process.releaseNonNull();
>         }
> 
>-        return createNewWebProcess(page.websiteDataStore());
>+        return createNewWebProcess(page->websiteDataStore());
>     };
> 
>     if (usesSingleWebProcess())
>@@ -2199,12 +2226,18 @@ void WebProcessPool::processForNavigationInternal(WebPageProxy& page, const API:
>             });
>         }
> 
>-        if (RefPtr<WebProcessProxy> process = WebProcessProxy::processForIdentifier(targetItem->itemID().processIdentifier)) {
>+        if (RefPtr<WebProcessProxy> process = WebProcessProxy::processForIdentifier(targetItem->lastProcessIdentifier())) {
>             // FIXME: Architecturally we do not currently support multiple WebPage's with the same ID in a given WebProcess.
>             // In the case where this WebProcess has a SuspendedPageProxy for this WebPage, we can throw it away to support
>             // WebProcess re-use.
>             removeAllSuspendedPagesForPage(page, process.get());
> 
>+            // Make sure we remove the process from the cache if it is in there since we're about to use it.
>+            if (process->isInProcessCache()) {
>+                auto removedProcess = webProcessCache().takeProcess(process->registrableDomain(), process->websiteDataStore());
>+                ASSERT_UNUSED(removedProcess, removedProcess.get() == process.get());
>+            }
>+
>             return completionHandler(process.releaseNonNull(), nullptr, "Using target back/forward item's process"_s);
>         }
>     }
>@@ -2228,7 +2261,6 @@ void WebProcessPool::processForNavigationInternal(WebPageProxy& page, const API:
> 
>     String reason = "Navigation is cross-site"_s;
>     
>-    auto registrableDomain = toRegistrableDomain(targetURL);
>     if (m_configuration->alwaysKeepAndReuseSwappedProcesses()) {
>         LOG(ProcessSwapping, "(ProcessSwapping) Considering re-use of a previously cached process for domain %s", registrableDomain.utf8().data());
> 
>@@ -2247,22 +2279,26 @@ void WebProcessPool::processForNavigationInternal(WebPageProxy& page, const API:
>         }
>     }
> 
>-    // Check if we have a suspended page for the given registrable domain and use its process if we do, for performance reasons.
>+    return completionHandler(createNewProcess(), nullptr, reason);
>+}
>+
>+RefPtr<WebProcessProxy> WebProcessPool::findReusableSuspendedPageProcess(const String& registrableDomain, WebPageProxy& page)
>+{
>     auto it = m_suspendedPages.findIf([&](auto& suspendedPage) {
>-        return suspendedPage->registrableDomain() == registrableDomain;
>+        return suspendedPage->registrableDomain() == registrableDomain && &suspendedPage->process().websiteDataStore() == &page.websiteDataStore();
>     });
>-    if (it != m_suspendedPages.end()) {
>-        Ref<WebProcessProxy> process = (*it)->process();
>+    if (it == m_suspendedPages.end())
>+        return nullptr;
> 
>-        // FIXME: If the SuspendedPage is for this page, then we need to destroy the suspended page as we do not support having
>-        // multiple WebPages with the same ID in a given WebProcess currently (https://bugs.webkit.org/show_bug.cgi?id=191166).
>-        if (&(*it)->page() == &page)
>-            m_suspendedPages.remove(it);
>+    Ref<WebProcessProxy> process = (*it)->process();
> 
>-        return completionHandler(WTFMove(process), nullptr, reason);
>-    }
>+    // FIXME: If the SuspendedPage is for this page, then we need to destroy the suspended page as we do not support having
>+    // multiple WebPages with the same ID in a given WebProcess currently (https://bugs.webkit.org/show_bug.cgi?id=191166).
>+    if (&(*it)->page() == &page)
>+        m_suspendedPages.remove(it);
> 
>-    return completionHandler(createNewProcess(), nullptr, reason);
>+
>+    return WTFMove(process);
> }
> 
> void WebProcessPool::addSuspendedPage(std::unique_ptr<SuspendedPageProxy>&& suspendedPage)
>diff --git a/Source/WebKit/UIProcess/WebProcessPool.h b/Source/WebKit/UIProcess/WebProcessPool.h
>index e574e1d7a62c4d7ecf3083d2f8330d98137e5fcd..ebff9bf97fa9696d327164ab6caee454baa2b2eb 100644
>--- a/Source/WebKit/UIProcess/WebProcessPool.h
>+++ b/Source/WebKit/UIProcess/WebProcessPool.h
>@@ -101,6 +101,7 @@ class WebAutomationSession;
> class WebContextSupplement;
> class WebPageGroup;
> class WebPageProxy;
>+class WebProcessCache;
> struct NetworkProcessCreationParameters;
> struct StatisticsData;
> struct WebProcessCreationParameters;
>@@ -176,6 +177,8 @@ public:
> 
>     void processDidFinishLaunching(WebProcessProxy*);
> 
>+    WebProcessCache& webProcessCache() { return m_webProcessCache.get(); }
>+
>     // Disconnect the process from the context.
>     void disconnectProcess(WebProcessProxy*);
> 
>@@ -464,6 +467,7 @@ public:
>     void removeSuspendedPage(SuspendedPageProxy&);
>     bool hasSuspendedPageFor(WebProcessProxy&, WebPageProxy* = nullptr) const;
>     unsigned maxSuspendedPageCount() const { return m_maxSuspendedPageCount; }
>+    RefPtr<WebProcessProxy> findReusableSuspendedPageProcess(const String&, WebPageProxy&);
> 
>     void didReachGoodTimeToPrewarm();
> 
>@@ -548,6 +552,8 @@ private:
>     void unregisterNotificationObservers();
> #endif
> 
>+    void setApplicationIsActive(bool);
>+
>     void addPlugInAutoStartOriginHash(const String& pageOrigin, unsigned plugInOriginHash, PAL::SessionID);
>     void plugInDidReceiveUserInteraction(unsigned plugInOriginHash, PAL::SessionID);
> 
>@@ -649,6 +655,8 @@ private:
> #if ENABLE(WEBPROCESS_WINDOWSERVER_BLOCKING)
>     RetainPtr<NSObject> m_scrollerStyleNotificationObserver;
> #endif
>+    RetainPtr<NSObject> m_activationObserver;
>+    RetainPtr<NSObject> m_deactivationObserver;
> 
>     std::unique_ptr<HighPerformanceGraphicsUsageSampler> m_highPerformanceGraphicsUsageSampler;
>     std::unique_ptr<PerActivityStateCPUUsageSampler> m_perActivityStateCPUUsageSampler;
>@@ -739,6 +747,7 @@ private:
>     Deque<std::unique_ptr<SuspendedPageProxy>> m_suspendedPages;
>     unsigned m_maxSuspendedPageCount { 0 };
> 
>+    UniqueRef<WebProcessCache> m_webProcessCache;
>     HashMap<String, RefPtr<WebProcessProxy>> m_swappedProcessesPerRegistrableDomain;
> 
>     HashMap<String, std::unique_ptr<WebCore::PrewarmInformation>> m_prewarmInformationPerRegistrableDomain;
>diff --git a/Source/WebKit/UIProcess/WebProcessProxy.cpp b/Source/WebKit/UIProcess/WebProcessProxy.cpp
>index e686828590a54805df3e31790ff85042eaf573ce..639b0b2ab053d62a0e3d8d3fcdd83c686e92a195 100644
>--- a/Source/WebKit/UIProcess/WebProcessProxy.cpp
>+++ b/Source/WebKit/UIProcess/WebProcessProxy.cpp
>@@ -46,6 +46,7 @@
> #include "WebPageGroup.h"
> #include "WebPageProxy.h"
> #include "WebPasteboardProxy.h"
>+#include "WebProcessCache.h"
> #include "WebProcessMessages.h"
> #include "WebProcessPool.h"
> #include "WebProcessProxyMessages.h"
>@@ -181,6 +182,23 @@ WebProcessProxy::~WebProcessProxy()
> #endif
> }
> 
>+void WebProcessProxy::setIsInProcessCache(bool value)
>+{
>+    ASSERT(m_isInProcessCache != value);
>+    m_isInProcessCache = value;
>+
>+    send(Messages::WebProcess::SetIsInProcessCache(m_isInProcessCache), 0);
>+
>+    if (m_isInProcessCache) {
>+        // WebProcessProxy objects normally keep the process pool alive but we do not want this to be the case
>+        // for cached processes or it would leak the pool.
>+        m_processPool.setIsWeak(IsWeak::Yes);
>+    } else {
>+        RELEASE_ASSERT(m_processPool);
>+        m_processPool.setIsWeak(IsWeak::No);
>+    }
>+}
>+
> void WebProcessProxy::getLaunchOptions(ProcessLauncher::LaunchOptions& launchOptions)
> {
>     launchOptions.processType = ProcessLauncher::ProcessType::Web;
>@@ -333,6 +351,7 @@ void WebProcessProxy::addExistingWebPage(WebPageProxy& webPage, uint64_t pageID,
> {
>     ASSERT(!m_pageMap.contains(pageID));
>     ASSERT(!globalPageMap().contains(pageID));
>+    ASSERT(!m_isInProcessCache);
> 
>     if (beginsUsingDataStore == BeginsUsingDataStore::Yes)
>         m_processPool->pageBeginUsingWebsiteDataStore(webPage);
>@@ -480,10 +499,36 @@ bool WebProcessProxy::fullKeyboardAccessEnabled()
> }
> #endif
> 
>+bool WebProcessProxy::hasProvisionalPageWithID(uint64_t pageID) const
>+{
>+    for (auto* provisionalPage : m_provisionalPages) {
>+        if (provisionalPage->page().pageID() == pageID)
>+            return true;
>+    }
>+    return false;
>+}
>+
>+bool WebProcessProxy::isAllowedToUpdateBackForwardItem(WebBackForwardListItem& item) const
>+{
>+    if (m_pageMap.contains(item.pageID()))
>+        return true;
>+
>+    if (hasProvisionalPageWithID(item.pageID()))
>+        return true;
>+
>+    if (item.suspendedPage() && item.suspendedPage()->page().pageID() == item.pageID() && &item.suspendedPage()->process() == this)
>+        return true;
>+
>+    return false;
>+}
>+
> void WebProcessProxy::updateBackForwardItem(const BackForwardListItemState& itemState)
> {
>-    if (auto* item = WebBackForwardListItem::itemForID(itemState.identifier))
>-        item->setPageState(itemState.pageState);
>+    auto* item = WebBackForwardListItem::itemForID(itemState.identifier);
>+    if (!item || !isAllowedToUpdateBackForwardItem(*item))
>+        return;
>+
>+    item->setPageState(itemState.pageState);
> }
> 
> #if ENABLE(NETSCAPE_PLUGIN_API)
>@@ -590,6 +635,11 @@ void WebProcessProxy::processDidTerminateOrFailedToLaunch()
>     auto pages = copyToVectorOf<RefPtr<WebPageProxy>>(m_pageMap.values());
>     auto provisionalPages = WTF::map(m_provisionalPages, [](auto* provisionalPage) { return makeWeakPtr(provisionalPage); });
> 
>+    if (m_isInProcessCache) {
>+        auto removedProcess = processPool().webProcessCache().takeProcess(registrableDomain(), websiteDataStore());
>+        ASSERT_UNUSED(removedProcess, removedProcess.get() == this);
>+    }
>+
>     shutDown();
> 
> #if ENABLE(PUBLIC_SUFFIX_LIST)
>@@ -769,17 +819,34 @@ void WebProcessProxy::didDestroyUserGestureToken(uint64_t identifier)
>     m_userInitiatedActionMap.remove(identifier);
> }
> 
>+bool WebProcessProxy::canBeAddedToWebProcessCache() const
>+{
>+    if (registrableDomain().isEmpty())
>+        return false;
>+
>+    if (isServiceWorkerProcess())
>+        return false;
>+
>+    if (WebKit::isInspectorProcessPool(processPool()))
>+        return false;
>+
>+    return true;
>+}
>+
> void WebProcessProxy::maybeShutDown()
> {
>     if (state() == State::Terminated || !canTerminateAuxiliaryProcess())
>         return;
> 
>+    if (canBeAddedToWebProcessCache() && processPool().webProcessCache().addProcess(registrableDomain(), *this))
>+        return;
>+
>     shutDown();
> }
> 
> bool WebProcessProxy::canTerminateAuxiliaryProcess()
> {
>-    if (!m_pageMap.isEmpty() || m_processPool->hasSuspendedPageFor(*this) || !m_provisionalPages.isEmpty())
>+    if (!m_pageMap.isEmpty() || m_processPool->hasSuspendedPageFor(*this) || !m_provisionalPages.isEmpty() || m_isInProcessCache)
>         return false;
> 
>     if (!m_processPool->shouldTerminate(this))
>@@ -1344,6 +1411,23 @@ void WebProcessProxy::activePagesDomainsForTesting(CompletionHandler<void(Vector
>     connection()->sendWithAsyncReply(Messages::WebProcess::GetActivePagesOriginsForTesting(), WTFMove(completionHandler));
> }
> 
>+void WebProcessProxy::didStartProvisionalLoadForMainFrame(const URL& url)
>+{
>+    // This process has been used for several registrable domains already.
>+    if (m_registrableDomain && m_registrableDomain->isNull())
>+        return;
>+
>+    auto registrableDomain = toRegistrableDomain(url);
>+    if (m_registrableDomain && *m_registrableDomain != registrableDomain) {
>+        // Null out registrable domain since this process has now been used for several domains.
>+        m_registrableDomain = String();
>+        return;
>+    }
>+
>+    // Associate the process with this registrable domain.
>+    m_registrableDomain = WTFMove(registrableDomain);
>+}
>+
> #if PLATFORM(WATCHOS)
> 
> void WebProcessProxy::takeBackgroundActivityTokenForFullscreenInput()
>diff --git a/Source/WebKit/UIProcess/WebProcessProxy.h b/Source/WebKit/UIProcess/WebProcessProxy.h
>index ea80979621e8162c82d6207cc3e2b4681a5f216f..376f3d57793e7bfc491c35363d208832d7df4437 100644
>--- a/Source/WebKit/UIProcess/WebProcessProxy.h
>+++ b/Source/WebKit/UIProcess/WebProcessProxy.h
>@@ -108,6 +108,10 @@ public:
> 
>     WebProcessPool& processPool() const { ASSERT(m_processPool); return *m_processPool.get(); }
> 
>+    String registrableDomain() const { return m_registrableDomain.valueOr(String()); }
>+    void setIsInProcessCache(bool);
>+    bool isInProcessCache() const { return m_isInProcessCache; }
>+
>     // FIXME: WebsiteDataStores should be made per-WebPageProxy throughout WebKit2
>     WebsiteDataStore& websiteDataStore() const { return m_websiteDataStore.get(); }
> 
>@@ -126,6 +130,7 @@ public:
> 
>     typename WebPageProxyMap::ValuesConstIteratorRange pages() const { return m_pageMap.values(); }
>     unsigned pageCount() const { return m_pageMap.size(); }
>+    unsigned provisionalPageCount() const { return m_provisionalPages.size(); }
>     unsigned visiblePageCount() const { return m_visiblePageCounter.value(); }
> 
>     void activePagesDomainsForTesting(CompletionHandler<void(Vector<String>&&)>&&); // This is what is reported to ActivityMonitor.
>@@ -249,6 +254,8 @@ public:
>     void shutDown();
>     void maybeShutDown();
> 
>+    void didStartProvisionalLoadForMainFrame(const URL&);
>+
> protected:
>     static uint64_t generatePageID();
>     WebProcessProxy(WebProcessPool&, WebsiteDataStore&, IsPrewarmed);
>@@ -274,6 +281,7 @@ private:
>     void didDestroyFrame(uint64_t);
>     void didDestroyUserGestureToken(uint64_t);
> 
>+    bool canBeAddedToWebProcessCache() const;
>     void shouldTerminate(bool& shouldTerminate);
> 
>     void createNewMessagePortChannel(const WebCore::MessagePortIdentifier& port1, const WebCore::MessagePortIdentifier& port2);
>@@ -286,6 +294,9 @@ private:
>     void didDeliverMessagePortMessages(uint64_t messageBatchIdentifier);
>     void didCheckProcessLocalPortForActivity(uint64_t callbackIdentifier, bool isLocallyReachable);
> 
>+    bool hasProvisionalPageWithID(uint64_t pageID) const;
>+    bool isAllowedToUpdateBackForwardItem(WebBackForwardListItem&) const;
>+
>     // Plugins
> #if ENABLE(NETSCAPE_PLUGIN_API)
>     void getPlugins(bool refresh, Vector<WebCore::PluginInfo>& plugins, Vector<WebCore::PluginInfo>& applicationPlugins, Optional<Vector<WebCore::SupportedPluginIdentifier>>&);
>@@ -371,7 +382,7 @@ private:
>     BackgroundProcessResponsivenessTimer m_backgroundResponsivenessTimer;
>     
>     RefPtr<WebConnectionToWebProcess> m_webConnection;
>-    WeakOrStrongPtr<WebProcessPool> m_processPool; // Pre-warmed processes do not hold a strong reference to their pool.
>+    WeakOrStrongPtr<WebProcessPool> m_processPool; // Pre-warmed and cached processes do not hold a strong reference to their pool.
> 
>     bool m_mayHaveUniversalFileReadSandboxExtension; // True if a read extension for "/" was ever granted - we don't track whether WebProcess still has it.
>     HashSet<String> m_localPathsWithAssumedReadAccess;
>@@ -394,6 +405,9 @@ private:
> 
>     HashMap<String, uint64_t> m_pageURLRetainCountMap;
> 
>+    Optional<String> m_registrableDomain;
>+    bool m_isInProcessCache { false };
>+
>     enum class NoOrMaybe { No, Maybe } m_isResponsive;
>     Vector<WTF::Function<void(bool webProcessIsResponsive)>> m_isResponsiveCallbacks;
> 
>diff --git a/Source/WebKit/WebKit.xcodeproj/project.pbxproj b/Source/WebKit/WebKit.xcodeproj/project.pbxproj
>index 821a06a3e37b64e5749a2a1f6e44a3304698c8b3..82bb5c76899b1b81ac00544188fd46a57aea932f 100644
>--- a/Source/WebKit/WebKit.xcodeproj/project.pbxproj
>+++ b/Source/WebKit/WebKit.xcodeproj/project.pbxproj
>@@ -3685,6 +3685,8 @@
> 		832AE2511BE2E8CD00FAAE10 /* NetworkCacheSpeculativeLoadManager.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = NetworkCacheSpeculativeLoadManager.cpp; sourceTree = "<group>"; };
> 		832ED1891E2FE13B006BA64A /* PerActivityStateCPUUsageSampler.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = PerActivityStateCPUUsageSampler.cpp; sourceTree = "<group>"; };
> 		832ED18A1E2FE13B006BA64A /* PerActivityStateCPUUsageSampler.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PerActivityStateCPUUsageSampler.h; sourceTree = "<group>"; };
>+		83397C6622124BD100B62388 /* WebProcessCache.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = WebProcessCache.cpp; sourceTree = "<group>"; };
>+		83397C6722124BD100B62388 /* WebProcessCache.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WebProcessCache.h; sourceTree = "<group>"; };
> 		834B250E1A831A8D00CFB150 /* NetworkCacheFileSystem.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = NetworkCacheFileSystem.h; sourceTree = "<group>"; };
> 		834B25101A842C8700CFB150 /* NetworkCacheStatistics.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = NetworkCacheStatistics.h; sourceTree = "<group>"; };
> 		8360349D1ACB34D600626549 /* WebSQLiteDatabaseTracker.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = WebSQLiteDatabaseTracker.cpp; sourceTree = "<group>"; };
>@@ -7490,6 +7492,8 @@
> 				BC574E611267D080006F0F12 /* WebPopupMenuProxy.h */,
> 				BCD597FE112B57BE00EC8C23 /* WebPreferences.cpp */,
> 				BCD597FD112B57BE00EC8C23 /* WebPreferences.h */,
>+				83397C6622124BD100B62388 /* WebProcessCache.cpp */,
>+				83397C6722124BD100B62388 /* WebProcessCache.h */,
> 				1AFA4B8D1A65A9E2006C4AB4 /* WebProcessLifetimeObserver.cpp */,
> 				1AFA4B8E1A65A9E2006C4AB4 /* WebProcessLifetimeObserver.h */,
> 				1AFA4B891A65A1D0006C4AB4 /* WebProcessLifetimeTracker.cpp */,
>diff --git a/Source/WebKit/WebProcess/WebProcess.cpp b/Source/WebKit/WebProcess/WebProcess.cpp
>index 2822050e4ab51a284912befc4d03ab252a0efdcf..23e8c3712683067ecc44e192ce63e9b15dbef636 100644
>--- a/Source/WebKit/WebProcess/WebProcess.cpp
>+++ b/Source/WebKit/WebProcess/WebProcess.cpp
>@@ -457,6 +457,23 @@ bool WebProcess::hasPageRequiringPageCacheWhileSuspended() const
>     return false;
> }
> 
>+void WebProcess::setIsInProcessCache(bool isInProcessCache)
>+{
>+#if PLATFORM(MAC)
>+    if (isInProcessCache) {
>+        ASSERT(m_processType == ProcessType::WebContent);
>+        m_processType = ProcessType::CachedWebContent;
>+    } else {
>+        ASSERT(m_processType == ProcessType::CachedWebContent);
>+        m_processType = ProcessType::WebContent;
>+    }
>+
>+    updateProcessName();
>+#else
>+    UNUSED_PARAM(isInProcessCache);
>+#endif
>+}
>+
> void WebProcess::markIsNoLongerPrewarmed()
> {
> #if PLATFORM(MAC)
>diff --git a/Source/WebKit/WebProcess/WebProcess.h b/Source/WebKit/WebProcess/WebProcess.h
>index b9ca2ee41707bc5bc62bb11bd4628efc4b270c3f..5bd000580c1f014bd39883737f0795ef64423d63 100644
>--- a/Source/WebKit/WebProcess/WebProcess.h
>+++ b/Source/WebKit/WebProcess/WebProcess.h
>@@ -267,6 +267,7 @@ private:
> 
>     void platformTerminate();
> 
>+    void setIsInProcessCache(bool);
>     void markIsNoLongerPrewarmed();
> 
>     void registerURLSchemeAsEmptyDocument(const String&);
>@@ -465,7 +466,7 @@ private:
>     std::unique_ptr<WebCore::CPUMonitor> m_cpuMonitor;
>     Optional<double> m_cpuLimit;
> 
>-    enum class ProcessType { Inspector, ServiceWorker, PrewarmedWebContent, WebContent };
>+    enum class ProcessType { Inspector, ServiceWorker, PrewarmedWebContent, CachedWebContent, WebContent };
>     ProcessType m_processType { ProcessType::WebContent };
>     String m_uiProcessName;
>     String m_securityOrigin;
>diff --git a/Source/WebKit/WebProcess/WebProcess.messages.in b/Source/WebKit/WebProcess/WebProcess.messages.in
>index 6f6ca362efc6286e89ff46dce802dbcbefe87723..3d73f2e9cc6206b7177f2e2de01abe9c86bd3570 100644
>--- a/Source/WebKit/WebProcess/WebProcess.messages.in
>+++ b/Source/WebKit/WebProcess/WebProcess.messages.in
>@@ -119,6 +119,7 @@ messages -> WebProcess LegacyReceiver {
>     CheckProcessLocalPortForActivity(struct WebCore::MessagePortIdentifier port, uint64_t callbackIdentifier)
>     MessagesAvailableForPort(struct WebCore::MessagePortIdentifier port)
> 
>+    SetIsInProcessCache(bool isInProcessCache)
>     MarkIsNoLongerPrewarmed()
>     UpdateActivePages()
>     GetActivePagesOriginsForTesting() -> (Vector<String> activeOrigins) Async
>diff --git a/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm b/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm
>index e77f7154db948e6bfd3697764c1a4b9e2fd3947d..d162516598a7183aac24b00fe262c25bcca87e00 100644
>--- a/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm
>+++ b/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm
>@@ -240,6 +240,9 @@ void WebProcess::updateProcessName()
>     case ProcessType::PrewarmedWebContent:
>         applicationName = [NSString stringWithFormat:WEB_UI_STRING("%@ Web Content (Prewarmed)", "Visible name of the web process. The argument is the application name."), (NSString *)m_uiProcessName];
>         break;
>+    case ProcessType::CachedWebContent:
>+        applicationName = [NSString stringWithFormat:WEB_UI_STRING("%@ Web Content (Cached)", "Visible name of the web process. The argument is the application name."), (NSString *)m_uiProcessName];
>+        break;
>     case ProcessType::WebContent:
>         applicationName = [NSString stringWithFormat:WEB_UI_STRING("%@ Web Content", "Visible name of the web process. The argument is the application name."), (NSString *)m_uiProcessName];
>         break;
>diff --git a/Tools/ChangeLog b/Tools/ChangeLog
>index 22cc6a5120d758a4269b0b4fe9ac3699325aa63d..1d54749b07f25f7b763d613ee99a01659806615e 100644
>--- a/Tools/ChangeLog
>+++ b/Tools/ChangeLog
>@@ -1,3 +1,15 @@
>+2019-02-13  Chris Dumez  <cdumez@apple.com>
>+
>+        [PSON] Introduce a WebContent Process cache
>+        https://bugs.webkit.org/show_bug.cgi?id=194594
>+        <rdar://problem/46793397>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Update API tests to turn on the WebContent Process cache.
>+
>+        * TestWebKitAPI/Tests/WebKitCocoa/ProcessSwapOnNavigation.mm:
>+
> 2019-02-12  Jiewen Tan  <jiewen_tan@apple.com>
> 
>         Further restricting webarchive loads
>diff --git a/Tools/TestWebKitAPI/Tests/WebKitCocoa/ProcessSwapOnNavigation.mm b/Tools/TestWebKitAPI/Tests/WebKitCocoa/ProcessSwapOnNavigation.mm
>index 22e1cd583f05f14dddda4481ca8b78c86b0112c4..c2778501858dbe8b7c5bc59c1bd440c5783b614e 100644
>--- a/Tools/TestWebKitAPI/Tests/WebKitCocoa/ProcessSwapOnNavigation.mm
>+++ b/Tools/TestWebKitAPI/Tests/WebKitCocoa/ProcessSwapOnNavigation.mm
>@@ -432,11 +432,18 @@ window.addEventListener('pageshow', function(event) {
> 
> #endif // PLATFORM(MAC)
> 
>-TEST(ProcessSwap, Basic)
>+static RetainPtr<_WKProcessPoolConfiguration> psonProcessPoolConfiguration()
> {
>     auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>     processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    processPoolConfiguration.get().usesWebProcessCache = YES;
>     processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    return processPoolConfiguration;
>+}
>+
>+TEST(ProcessSwap, Basic)
>+{
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -481,9 +488,7 @@ TEST(ProcessSwap, Basic)
> 
> TEST(ProcessSwap, LoadAfterPolicyDecision)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -519,9 +524,7 @@ TEST(ProcessSwap, LoadAfterPolicyDecision)
> 
> TEST(ProcessSwap, KillWebContentProcessAfterServerRedirectPolicyDecision)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -570,9 +573,7 @@ TEST(ProcessSwap, KillWebContentProcessAfterServerRedirectPolicyDecision)
> 
> TEST(ProcessSwap, NoSwappingForeTLDPlus2)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -607,8 +608,7 @@ TEST(ProcessSwap, NoSwappingForeTLDPlus2)
> 
> TEST(ProcessSwap, Back)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -715,8 +715,7 @@ static const char* pageWithFragmentTestBytes = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, HistoryNavigationToFragmentURL)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -768,8 +767,7 @@ TEST(ProcessSwap, HistoryNavigationToFragmentURL)
> 
> TEST(ProcessSwap, SuspendedPageDiesAfterBackForwardListItemIsGone)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -801,7 +799,7 @@ TEST(ProcessSwap, SuspendedPageDiesAfterBackForwardListItemIsGone)
>     EXPECT_NE(webkitPID, applePID);
> 
>     // webkit.org + apple.com processes.
>-    EXPECT_EQ(2U, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(2U, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
> 
>     [webView goBack]; // Back to webkit.org.
>     TestWebKitAPI::Util::run(&done);
>@@ -810,7 +808,7 @@ TEST(ProcessSwap, SuspendedPageDiesAfterBackForwardListItemIsGone)
>     EXPECT_EQ(webkitPID, [webView _webProcessIdentifier]);
> 
>     // webkit.org + apple.com processes.
>-    EXPECT_EQ(2U, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(2U, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
> 
>     request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"pson://www.webkit.org/main2.html"]];
>     [webView loadRequest:request];
>@@ -821,15 +819,14 @@ TEST(ProcessSwap, SuspendedPageDiesAfterBackForwardListItemIsGone)
>     EXPECT_EQ(webkitPID, [webView _webProcessIdentifier]);
> 
>     // apple.com is not longer present in the back/forward list and there should therefore be no-suspended page for it.
>-    while ([processPool _webProcessCountIgnoringPrewarmed] > 1u)
>+    while ([processPool _webProcessCountIgnoringPrewarmedAndCached] > 1u)
>         TestWebKitAPI::Util::spinRunLoop();
> }
> 
> #if PLATFORM(MAC)
> TEST(ProcessSwap, SuspendedPagesInActivityMonitor)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -917,8 +914,7 @@ TEST(ProcessSwap, SuspendedPagesInActivityMonitor)
> 
> TEST(ProcessSwap, BackWithoutSuspendedPage)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -975,8 +971,7 @@ TEST(ProcessSwap, BackWithoutSuspendedPage)
> 
> TEST(ProcessSwap, BackNavigationAfterSessionRestore)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1032,8 +1027,7 @@ TEST(ProcessSwap, BackNavigationAfterSessionRestore)
> 
> TEST(ProcessSwap, CrossSiteWindowOpenNoOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1072,8 +1066,7 @@ TEST(ProcessSwap, CrossSiteWindowOpenNoOpener)
> 
> TEST(ProcessSwap, CrossOriginButSameSiteWindowOpenNoOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1112,8 +1105,7 @@ TEST(ProcessSwap, CrossOriginButSameSiteWindowOpenNoOpener)
> 
> TEST(ProcessSwap, CrossSiteWindowOpenWithOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     processPoolConfiguration.get().processSwapsOnWindowOpenWithOpener = YES;
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>@@ -1153,8 +1145,7 @@ TEST(ProcessSwap, CrossSiteWindowOpenWithOpener)
> 
> TEST(ProcessSwap, SameSiteWindowOpenNoOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1192,8 +1183,7 @@ TEST(ProcessSwap, SameSiteWindowOpenNoOpener)
> 
> TEST(ProcessSwap, CrossSiteBlankTargetWithOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1232,8 +1222,7 @@ TEST(ProcessSwap, CrossSiteBlankTargetWithOpener)
> 
> TEST(ProcessSwap, CrossSiteBlankTargetImplicitNoOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1272,8 +1261,7 @@ TEST(ProcessSwap, CrossSiteBlankTargetImplicitNoOpener)
> 
> TEST(ProcessSwap, CrossSiteBlankTargetNoOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1312,8 +1300,7 @@ TEST(ProcessSwap, CrossSiteBlankTargetNoOpener)
> 
> TEST(ProcessSwap, SameSiteBlankTargetNoOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1354,8 +1341,7 @@ TEST(ProcessSwap, SameSiteBlankTargetNoOpener)
> 
> TEST(ProcessSwap, ServerRedirectFromNewWebView)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1388,8 +1374,7 @@ TEST(ProcessSwap, ServerRedirectFromNewWebView)
> 
> TEST(ProcessSwap, ServerRedirect)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1435,8 +1420,7 @@ TEST(ProcessSwap, ServerRedirect)
> TEST(ProcessSwap, ServerRedirect2)
> {
>     // This tests a load that *starts out* to the same origin as the previous load, but then redirects to a new origin.
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1493,8 +1477,7 @@ TEST(ProcessSwap, ServerRedirect2)
> 
> TEST(ProcessSwap, TerminateProcessRightAfterSwap)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1533,8 +1516,7 @@ static const char* linkToWebKitBytes = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, PolicyCancelAfterServerRedirect)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1587,8 +1569,7 @@ TEST(ProcessSwap, PolicyCancelAfterServerRedirect)
> 
> TEST(ProcessSwap, CrossSiteDownload)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1648,8 +1629,7 @@ static const char* systemPreviewCrossOriginTestBytes = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, SameOriginSystemPreview)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1685,8 +1665,7 @@ TEST(ProcessSwap, SameOriginSystemPreview)
> 
> TEST(ProcessSwap, CrossOriginSystemPreview)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1725,7 +1704,7 @@ TEST(ProcessSwap, CrossOriginSystemPreview)
> enum class ShouldEnablePSON { No, Yes };
> static void runClientSideRedirectTest(ShouldEnablePSON shouldEnablePSON)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     processPoolConfiguration.get().processSwapsOnNavigation = shouldEnablePSON == ShouldEnablePSON::Yes ? YES : NO;
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>@@ -1860,9 +1839,7 @@ TEST(ProcessSwap, CrossSiteClientSideRedirectWithPSON)
> 
> TEST(ProcessSwap, CrossSiteClientSideRedirectFromFileURL)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1891,15 +1868,14 @@ TEST(ProcessSwap, CrossSiteClientSideRedirectFromFileURL)
>     auto pid2 = [webView _webProcessIdentifier];
>     EXPECT_NE(pid1, pid2);
> 
>-    EXPECT_EQ(1U, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(1U, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
>     EXPECT_TRUE(willPerformClientRedirect);
>     EXPECT_TRUE(didPerformClientRedirect);
> }
> 
> TEST(ProcessSwap, NavigateBackAfterClientSideRedirect)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -1973,7 +1949,7 @@ TEST(ProcessSwap, NavigateBackAfterClientSideRedirect)
> 
> static void runNavigationWithLockedHistoryTest(ShouldEnablePSON shouldEnablePSON)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     processPoolConfiguration.get().processSwapsOnNavigation = shouldEnablePSON == ShouldEnablePSON::Yes ? YES : NO;
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>@@ -2072,8 +2048,7 @@ window.onload = function(evt) {
> 
> TEST(ProcessSwap, SessionStorage)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2129,8 +2104,7 @@ TEST(ProcessSwap, SessionStorage)
> 
> TEST(ProcessSwap, ReuseSuspendedProcess)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2190,8 +2164,7 @@ var myWorker = new Worker('worker.js');
> 
> TEST(ProcessSwap, ReuseSuspendedProcessEvenIfPageCacheFails)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2243,8 +2216,7 @@ TEST(ProcessSwap, ReuseSuspendedProcessEvenIfPageCacheFails)
> 
> TEST(ProcessSwap, ReuseSuspendedProcessOnBackEvenIfPageCacheFails)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2292,8 +2264,7 @@ static const char* withSubframesTestBytes = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, HistoryItemIDConfusion)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2358,8 +2329,7 @@ TEST(ProcessSwap, HistoryItemIDConfusion)
> 
> TEST(ProcessSwap, GoToSecondItemInBackHistory)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2445,11 +2415,9 @@ enum class RetainPageInBundle { No, Yes };
> 
> void testReuseSuspendedProcessForRegularNavigation(RetainPageInBundle retainPageInBundle)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     if (retainPageInBundle == RetainPageInBundle::Yes)
>         [processPoolConfiguration setInjectedBundleURL:[[NSBundle mainBundle] URLForResource:@"TestWebKitAPI" withExtension:@"wkbundle"]];
>-
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
>     if (retainPageInBundle == RetainPageInBundle::Yes)
>         [processPool _setObject:@"BundleRetainPagePlugIn" forBundleParameter:TestWebKitAPI::Util::TestPlugInClassNameParameter];
>@@ -2525,8 +2493,7 @@ static const char* mainFramesOnlySubframe2 = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, MainFramesOnly)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2571,8 +2538,7 @@ onload = () => {
> 
> TEST(ProcessSwap, PageZoomLevelAfterSwap)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2648,9 +2614,7 @@ static const char* navigateBeforePageLoadEndBytes = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, NavigateCrossSiteBeforePageLoadEnd)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>-    [processPoolConfiguration setPrewarmsProcessesAutomatically:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2679,8 +2643,7 @@ TEST(ProcessSwap, NavigateCrossSiteBeforePageLoadEnd)
> 
> TEST(ProcessSwap, DoSameSiteNavigationAfterCrossSiteProvisionalLoadStarted)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2721,8 +2684,7 @@ TEST(ProcessSwap, DoSameSiteNavigationAfterCrossSiteProvisionalLoadStarted)
> 
> TEST(ProcessSwap, SuspendedPageLimit)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2771,13 +2733,12 @@ TEST(ProcessSwap, SuspendedPageLimit)
>     EXPECT_EQ(5u, seenPIDs.size());
> 
>     // But not all of those processes should still be alive (1 visible, maximumSuspendedPageCount suspended).
>-    EXPECT_EQ([processPool _webProcessCountIgnoringPrewarmed], (1U + maximumSuspendedPageCount));
>+    EXPECT_EQ([processPool _webProcessCountIgnoringPrewarmedAndCached], (1U + maximumSuspendedPageCount));
> }
> 
> TEST(ProcessSwap, PageCache1)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2802,7 +2763,7 @@ TEST(ProcessSwap, PageCache1)
> 
>     auto pidAfterLoad1 = [webView _webProcessIdentifier];
> 
>-    EXPECT_EQ(1u, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(1u, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
> 
>     request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"pson://www.apple.com/main.html"]];
> 
>@@ -2812,7 +2773,7 @@ TEST(ProcessSwap, PageCache1)
> 
>     auto pidAfterLoad2 = [webView _webProcessIdentifier];
> 
>-    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
>     EXPECT_NE(pidAfterLoad1, pidAfterLoad2);
> 
>     [webView goBack];
>@@ -2823,7 +2784,7 @@ TEST(ProcessSwap, PageCache1)
> 
>     auto pidAfterLoad3 = [webView _webProcessIdentifier];
> 
>-    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
>     EXPECT_EQ(pidAfterLoad1, pidAfterLoad3);
>     EXPECT_EQ(1u, [receivedMessages count]);
>     EXPECT_TRUE([receivedMessages.get()[0] isEqualToString:@"Was persisted" ]);
>@@ -2837,7 +2798,7 @@ TEST(ProcessSwap, PageCache1)
> 
>     auto pidAfterLoad4 = [webView _webProcessIdentifier];
> 
>-    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
>     EXPECT_EQ(pidAfterLoad2, pidAfterLoad4);
>     EXPECT_EQ(2u, [receivedMessages count]);
>     EXPECT_TRUE([receivedMessages.get()[1] isEqualToString:@"Was persisted" ]);
>@@ -2846,9 +2807,7 @@ TEST(ProcessSwap, PageCache1)
> 
> TEST(ProcessSwap, NumberOfPrewarmedProcesses)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>-    [processPoolConfiguration setPrewarmsProcessesAutomatically:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2866,7 +2825,7 @@ TEST(ProcessSwap, NumberOfPrewarmedProcesses)
>     done = false;
> 
>     EXPECT_EQ(2u, [processPool _webProcessCount]);
>-    EXPECT_EQ(1u, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(1u, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
>     EXPECT_TRUE([processPool _hasPrewarmedWebProcess]);
> 
>     request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"pson://www.google.com/main.html"]];
>@@ -2875,7 +2834,7 @@ TEST(ProcessSwap, NumberOfPrewarmedProcesses)
>     done = false;
> 
>     EXPECT_EQ(3u, [processPool _webProcessCount]);
>-    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmed]);
>+    EXPECT_EQ(2u, [processPool _webProcessCountIgnoringPrewarmedAndCached]);
>     EXPECT_TRUE([processPool _hasPrewarmedWebProcess]);
> }
> 
>@@ -2897,8 +2856,7 @@ window.addEventListener('pagehide', function(event) {
> 
> TEST(ProcessSwap, PageShowHide)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -2989,8 +2947,7 @@ window.addEventListener('load', function(event) {
> 
> TEST(ProcessSwap, LoadUnload)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3066,8 +3023,7 @@ TEST(ProcessSwap, LoadUnload)
> 
> TEST(ProcessSwap, WebInspector)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3129,8 +3085,7 @@ link.href = URL.createObjectURL(blob);
> 
> TEST(ProcessSwap, SameOriginBlobNavigation)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3164,8 +3119,7 @@ TEST(ProcessSwap, SameOriginBlobNavigation)
> 
> TEST(ProcessSwap, CrossOriginBlobNavigation)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3223,8 +3177,7 @@ TEST(ProcessSwap, CrossOriginBlobNavigation)
> 
> TEST(ProcessSwap, NavigateToAboutBlank)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3257,8 +3210,7 @@ TEST(ProcessSwap, NavigateToAboutBlank)
> 
> TEST(ProcessSwap, NavigateToDataURL)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3291,9 +3243,7 @@ TEST(ProcessSwap, NavigateToDataURL)
> 
> TEST(ProcessSwap, ProcessReuse)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>-    [processPoolConfiguration setAlwaysKeepAndReuseSwappedProcesses:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3338,9 +3288,7 @@ TEST(ProcessSwap, ProcessReuse)
> 
> TEST(ProcessSwap, ProcessReuseeTLDPlus2)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>-    [processPoolConfiguration setAlwaysKeepAndReuseSwappedProcesses:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3385,8 +3333,7 @@ TEST(ProcessSwap, ProcessReuseeTLDPlus2)
> 
> TEST(ProcessSwap, ConcurrentHistoryNavigations)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3455,8 +3402,7 @@ TEST(ProcessSwap, ConcurrentHistoryNavigations)
> 
> TEST(ProcessSwap, NavigateToInvalidURL)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3507,8 +3453,7 @@ onpageshow = function(event) {
> 
> TEST(ProcessSwap, NavigateToDataURLThenBack)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     processPoolConfiguration.get().pageCacheEnabled = NO;
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>@@ -3543,8 +3488,7 @@ TEST(ProcessSwap, NavigateToDataURLThenBack)
> 
> TEST(ProcessSwap, NavigateCrossSiteWithPageCacheDisabled)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     processPoolConfiguration.get().pageCacheEnabled = NO;
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>@@ -3634,8 +3578,7 @@ static const char* navigateBackFromJSBytes = R"PSONRESOURCE(
> 
> TEST(ProcessSwap, NavigateToCrossSiteThenBackFromJS)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     processPoolConfiguration.get().pageCacheEnabled = NO;
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>@@ -3675,8 +3618,7 @@ TEST(ProcessSwap, NavigateToCrossSiteThenBackFromJS)
> 
> TEST(ProcessSwap, ClosePageAfterCrossSiteProvisionalLoad)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3734,8 +3676,7 @@ @end
> 
> TEST(ProcessSwap, LoadingStateAfterPolicyDecision)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3940,9 +3881,7 @@ TEST(ProcessSwap, OpenerLinkAfterAPIControlledProcessSwappingOfOpenee)
> enum class ExpectSwap { No, Yes };
> static void runProcessSwapDueToRelatedWebViewTest(NSURL* relatedViewURL, NSURL* targetURL, ExpectSwap expectSwap)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webView1Configuration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -3998,9 +3937,7 @@ TEST(ProcessSwap, NoProcessSwapDueToRelatedView)
> 
> TEST(ProcessSwap, TerminatedSuspendedPageProcess)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4063,8 +4000,7 @@ TEST(ProcessSwap, TerminatedSuspendedPageProcess)
> 
> TEST(ProcessSwap, NavigateBackAndForth)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4115,8 +4051,7 @@ TEST(ProcessSwap, NavigateBackAndForth)
> 
> TEST(ProcessSwap, SwapOnLoadHTMLString)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4159,9 +4094,7 @@ TEST(ProcessSwap, SwapOnLoadHTMLString)
> 
> TEST(ProcessSwap, UsePrewarmedProcessAfterTerminatingNetworkProcess)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto websiteDataStoreConfiguration = adoptNS([[_WKWebsiteDataStoreConfiguration alloc] init]);
>@@ -4195,8 +4128,7 @@ TEST(ProcessSwap, UsePrewarmedProcessAfterTerminatingNetworkProcess)
> 
> TEST(ProcessSwap, UseSessionCookiesAfterProcessSwapInPrivateBrowsing)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
>     RetainPtr<WKWebsiteDataStore> ephemeralStore = [WKWebsiteDataStore nonPersistentDataStore];
> 
>@@ -4255,8 +4187,7 @@ TEST(ProcessSwap, UseSessionCookiesAfterProcessSwapInPrivateBrowsing)
> 
> TEST(ProcessSwap, TerminateProcessAfterProcessSwap)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4309,8 +4240,7 @@ TEST(ProcessSwap, TerminateProcessAfterProcessSwap)
> 
> TEST(ProcessSwap, NavigateCrossOriginWithOpenee)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4387,8 +4317,7 @@ function saveOpenee()
> 
> TEST(ProcessSwap, NavigateCrossOriginWithOpener)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4516,8 +4445,7 @@ TEST(ProcessSwap, NavigateCrossOriginWithOpener)
> 
> TEST(ProcessSwap, GoBackToSuspendedPageWithMainFrameIDThatIsNotOne)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4607,8 +4535,7 @@ body {
> 
> TEST(ProcessSwap, ScrollPositionRestoration)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4687,8 +4614,7 @@ TEST(ProcessSwap, ContentBlockingAfterProcessSwap)
>     TestWebKitAPI::Util::run(&done);
>     done = false;
> 
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    [processPoolConfiguration setProcessSwapsOnNavigation:YES];
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);
>@@ -4810,10 +4736,7 @@ navigator.mediaDevices.getUserMedia({video: true});
> 
> TEST(ProcessSwap, GetUserMediaCaptureState)
> {
>-    auto processPoolConfiguration = adoptNS([[_WKProcessPoolConfiguration alloc] init]);
>-    processPoolConfiguration.get().processSwapsOnNavigation = YES;
>-    processPoolConfiguration.get().prewarmsProcessesAutomatically = YES;
>-
>+    auto processPoolConfiguration = psonProcessPoolConfiguration();
>     auto processPool = adoptNS([[WKProcessPool alloc] _initWithConfiguration:processPoolConfiguration.get()]);
> 
>     auto webViewConfiguration = adoptNS([[WKWebViewConfiguration alloc] init]);

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Attachments on bug 194594: 361952 | 361953 | 361986 | 362022 | 362026