Attachment 411934 Details for Bug 217566 – Patch

[patch] Patch

bug-217566-20201020162216.patch (text/plain), 85.14 KB, created by Said Abou-Hallawa on 2020-10-20 16:22:17 PDT

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Creator: Said Abou-Hallawa

Created: 2020-10-20 16:22:17 PDT

Size: 85.14 KB

patch

obsolete

>Subversion Revision: 268711
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index 0faeb9117dd81ac95f2e0d0bcedfe798ee3975d1..9626f1de5716461f38dd94f9fddb865a3dda152c 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,88 @@
>+2020-10-20  Said Abou-Hallawa  <said@apple.com>
>+
>+        [GPU Process]: Implement DisplayList::DrawImageBuffer item
>+        https://bugs.webkit.org/show_bug.cgi?id=217566
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Add the DrawImageBuffer DisplayList item. It will be used only for GPU
>+        rendering. The remoteResourceIdentifier of the source ImageBuffer will
>+        be recorded. For details on how drawing an ImageBuffer to another 
>+        ImageBuffer works see the WebKit ChangeLog.
>+
>+        * platform/graphics/GraphicsContext.cpp:
>+        (WebCore::GraphicsContext::drawImageBuffer):
>+        * platform/graphics/GraphicsContextImpl.h:
>+        * platform/graphics/cairo/GraphicsContextImplCairo.cpp:
>+        (WebCore::GraphicsContextImplCairo::drawImageBuffer):
>+        * platform/graphics/cairo/GraphicsContextImplCairo.h:
>+        * platform/graphics/displaylists/DisplayList.h:
>+        * platform/graphics/displaylists/DisplayListItems.cpp:
>+        (WebCore::DisplayList::Item::sizeInBytes):
>+        (WebCore::DisplayList::DrawImageBuffer::DrawImageBuffer):
>+        (WebCore::DisplayList::DrawImageBuffer::apply const):
>+        (WebCore::DisplayList::operator<<):
>+        * platform/graphics/displaylists/DisplayListItems.h:
>+        (WebCore::DisplayList::DrawImageBuffer::create):
>+        (WebCore::DisplayList::DrawImageBuffer::remoteResourceIdentifier const):
>+        (WebCore::DisplayList::DrawImageBuffer::source const):
>+        (WebCore::DisplayList::DrawImageBuffer::destinationRect const):
>+        (WebCore::DisplayList::DrawImageBuffer::options const):
>+        (WebCore::DisplayList::DrawImageBuffer::encode const):
>+        (WebCore::DisplayList::DrawImageBuffer::decode):
>+        (WebCore::DisplayList::Item::encode const):
>+        (WebCore::DisplayList::Item::decode):
>+        * platform/graphics/displaylists/DisplayListRecorder.cpp:
>+        (WebCore::DisplayList::Recorder::Recorder):
>+        (WebCore::DisplayList::Recorder::drawImageBuffer):
>+        * platform/graphics/displaylists/DisplayListRecorder.h:
>+        (WebCore::DisplayList::Recorder::Delegate::lockRemoteImageBuffer):
>+        * platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.cpp:
>+        (Nicosia::CairoOperationRecorder::drawImageBuffer):
>+        * platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.h:
>+
>+2020-10-19  Said Abou-Hallawa  <sabouhallawa@apple.com>
>+
>+        [GPU Process]: Introduce RemoteResourceCacheProxy to manage the remote resources in Web Process
>+        https://bugs.webkit.org/show_bug.cgi?id=217558
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Rename Recorder::Observer to Recorder::Delegate because it will be responsible
>+        for creating DisplayListItems in future patches. So it will not be just
>+        an observer. Also do not make DisplayList::ImageBuffer a superclass of it.
>+        RemoteImageBufferProxy, which is a superclass of DisplayList::ImageBuffer,
>+        will be the superclass of Recorder::Delegate.
>+
>+        Make ImageBufferBackend::isAccelerated a static member instead of a virtual
>+        method. RemoteRenderingBackendProxy would want to know whether the backend
>+        of an ImageBuffer isAccelerated or not without having to create it.
>+        ImageBufferBackend::isAccelerated will be set to false and
>+        ImageBufferIOSurfaceBackend::isAccelerated will be set to true.
>+
>+        * platform/graphics/ConcreteImageBuffer.h:
>+        * platform/graphics/ImageBuffer.h:
>+        (WebCore::ImageBuffer::remoteResourceIdentifier const):
>+        * platform/graphics/ImageBufferBackend.h:
>+        (WebCore::ImageBufferBackend::isAccelerated const): Deleted.
>+        * platform/graphics/RemoteResourceIdentifier.h:
>+        * platform/graphics/cg/ImageBufferIOSurfaceBackend.cpp:
>+        (WebCore::ImageBufferIOSurfaceBackend::isAccelerated const): Deleted.
>+        * platform/graphics/cg/ImageBufferIOSurfaceBackend.h:
>+        * platform/graphics/displaylists/DisplayListDrawingContext.cpp:
>+        (WebCore::DisplayList::DrawingContext::DrawingContext):
>+        * platform/graphics/displaylists/DisplayListDrawingContext.h:
>+        (WebCore::DisplayList::DrawingContext::DrawingContext):
>+        * platform/graphics/displaylists/DisplayListImageBuffer.h:
>+        (WebCore::DisplayList::ImageBuffer::ImageBuffer):
>+        * platform/graphics/displaylists/DisplayListRecorder.cpp:
>+        (WebCore::DisplayList::Recorder::Recorder):
>+        (WebCore::DisplayList::Recorder::willAppendItem):
>+        * platform/graphics/displaylists/DisplayListRecorder.h:
>+        (WebCore::DisplayList::Recorder::Delegate::~Delegate):
>+        (WebCore::DisplayList::Recorder::Observer::~Observer): Deleted.
>+        (WebCore::DisplayList::Recorder::Observer::willAppendItem): Deleted.
>+
> 2020-10-19  Alexey Shvayka  <shvaikalesh@gmail.com>
> 
>         [WebIDL] %Interface%.prototype.constructor should be defined on [[Set]] receiver
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index d7d684bcc0d76b173378092a27977ed27e0b7716..7478c0a5f61d04f67665ccaf3f39128fade92550 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,104 @@
>+2020-10-20  Said Abou-Hallawa  <said@apple.com>
>+
>+        [GPU Process]: Implement DisplayList::DrawImageBuffer item
>+        https://bugs.webkit.org/show_bug.cgi?id=217566
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        The sequence in the Web Process is the following:
>+
>+        -- GraphicsContext::drawImageBuffer() uses DisplayList::Recorder to check
>+           whether it is appropriate to create a DrawImageBuffer item or not.
>+
>+        -- DisplayList::Recorder::drawImageBuffer() uses the delegate to see if
>+           the ImageBuffer is remote or not and whether it can be locked till 
>+           replaying back the DisplayList in the GPU side. 
>+
>+        -- RemoteImageBufferProxy inherits DisplayList::Recorder::Delegate. So its
>+           lockRemoteImageBuffer() is called.
>+
>+        -- If the ImageBuffer can be locked, a DrawImageBufferItem is created with
>+           the ImageBuffer::remoteResourceIdentifier().
>+
>+        The sequence in the GPU Process is the following:
>+
>+        -- When replaying back the DisplayList, DisplayList::Replayer will call
>+           its delegate to check if it wants to apply the DrawImageBuffer.
>+
>+        -- Because RemoteImageBuffer inherits DisplayList::Replayer::Delegate,
>+           RemoteImageBuffer::apply() will be called.
>+
>+        -- RemoteImageBuffer will call RemoteRenderingBackend::applyResourceItem()
>+           which will check whether the item's remoteResourceIdentifier is one of 
>+           the ImageBuffers in its RemoteResourceCache or not.
>+
>+        -- If there is a cached ImageBuffer, RemoteRenderingBackend::applyResourceItem()
>+           will draw to GraphicsContext.
>+
>+        * GPUProcess/graphics/RemoteImageBuffer.h:
>+        * GPUProcess/graphics/RemoteRenderingBackend.cpp:
>+        (WebKit::RemoteRenderingBackend::applyResourceItem):
>+        * GPUProcess/graphics/RemoteRenderingBackend.h:
>+        * WebProcess/GPU/graphics/RemoteImageBufferProxy.h:
>+        * WebProcess/GPU/graphics/RemoteResourceCacheProxy.cpp:
>+        (WebKit::RemoteResourceCacheProxy::releaseImageBuffer):
>+        (WebKit::RemoteResourceCacheProxy::lockRemoteImageBufferForRemoteClient):
>+        (WebKit::RemoteResourceCacheProxy::lockRemoteResourceForRemoteClient):
>+        (WebKit::RemoteResourceCacheProxy::releaseRemoteResource):
>+        (WebKit::RemoteResourceCacheProxy::unlockRemoteResourcesForRemoteClient):
>+        * WebProcess/GPU/graphics/RemoteResourceCacheProxy.h:
>+
>+2020-10-19  Said Abou-Hallawa  <sabouhallawa@apple.com>
>+
>+        [GPU Process]: Introduce RemoteResourceCacheProxy to manage the remote resources in Web Process
>+        https://bugs.webkit.org/show_bug.cgi?id=217558
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Remove RemoteImageBufferMessageHandlerProxy and move sending the messages
>+        to RemoteRenderingBackendProxy.
>+
>+        To allow casting ImageBuffer to RemoteImageBufferProxy, a new method named
>+        remoteResourceIdentifier() is added to IamgeBuffer and it is only overridden
>+        by RemoteImageBufferProxy. This method is used in SPECIALIZE_TYPE_TRAITS
>+        macros along with IamgeBuffer::isAccelerated().
>+
>+        Introduce RemoteResourceCacheProxy which will manage caching and releasing
>+        the RemoteImageBufferProxy. Caching NativeImage will be added to it in
>+        future patches. More about controlling the life cycles of remote resources 
>+        will be added with supporting drawing remote resources to remote client.
>+
>+        * Sources.txt:
>+        * WebKit.xcodeproj/project.pbxproj:
>+        * WebProcess/GPU/graphics/PlatformRemoteImageBufferProxy.h:
>+        (isType):
>+        * WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.cpp: Removed.
>+        * WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.h: Removed.
>+        * WebProcess/GPU/graphics/RemoteImageBufferProxy.h:
>+        (WebKit::RemoteImageBufferProxy::create):
>+        (WebKit::RemoteImageBufferProxy::~RemoteImageBufferProxy):
>+        (WebKit::RemoteImageBufferProxy::createBackend):
>+        (WebKit::RemoteImageBufferProxy::commitFlushDisplayList):
>+        (WebKit::RemoteImageBufferProxy::RemoteImageBufferProxy):
>+        (WebKit::RemoteImageBufferProxy::isPendingFlush const):
>+        * WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp:
>+        (WebKit::RemoteRenderingBackendProxy::createImageBuffer):
>+        (WebKit::RemoteRenderingBackendProxy::getImageData):
>+        (WebKit::RemoteRenderingBackendProxy::flushDisplayList):
>+        (WebKit::RemoteRenderingBackendProxy::flushDisplayListAndCommit):
>+        (WebKit::RemoteRenderingBackendProxy::releaseRemoteResource):
>+        (WebKit::RemoteRenderingBackendProxy::imageBufferBackendWasCreated):
>+        (WebKit::RemoteRenderingBackendProxy::flushDisplayListWasCommitted):
>+        * WebProcess/GPU/graphics/RemoteRenderingBackendProxy.h:
>+        (WebKit::RemoteRenderingBackendProxy::remoteResourceCacheProxy):
>+        (WebKit::RemoteRenderingBackendProxy::renderingBackendIdentifier const): Deleted.
>+        * WebProcess/GPU/graphics/RemoteResourceCacheProxy.cpp: Copied from Source/WebCore/platform/graphics/RemoteResourceIdentifier.h.
>+        (WebKit::RemoteResourceCacheProxy::RemoteResourceCacheProxy):
>+        (WebKit::RemoteResourceCacheProxy::cacheImageBuffer):
>+        (WebKit::RemoteResourceCacheProxy::cachedImageBuffer):
>+        (WebKit::RemoteResourceCacheProxy::releaseImageBuffer):
>+        * WebProcess/GPU/graphics/RemoteResourceCacheProxy.h: Copied from Source/WebKit/WebProcess/GPU/graphics/PlatformRemoteImageBufferProxy.h.
>+
> 2020-10-19  Peng Liu  <peng.liu6@apple.com>
> 
>         Two feature flag names are incorrect
>diff --git a/Source/WebCore/platform/graphics/ConcreteImageBuffer.h b/Source/WebCore/platform/graphics/ConcreteImageBuffer.h
>index c6c19e1289f48b020ea78bce39d106c3db93b07d..8697395fa4c8d0851c7b7790406e61c918fcea50 100644
>--- a/Source/WebCore/platform/graphics/ConcreteImageBuffer.h
>+++ b/Source/WebCore/platform/graphics/ConcreteImageBuffer.h
>@@ -50,13 +50,8 @@ public:
>             return nullptr;
>         return std::unique_ptr<ImageBufferType>(new ImageBufferType(WTFMove(backend), std::forward<Arguments>(arguments)...));
>     }
>-    
>-    bool isAccelerated() const override
>-    {
>-        if (auto* backend = ensureBackendCreated())
>-            return backend->isAccelerated();
>-        return false;
>-    }
>+
>+    bool isAccelerated() const override { return BackendType::isAccelerated; }
> 
> protected:
>     ConcreteImageBuffer(std::unique_ptr<BackendType>&& backend)
>diff --git a/Source/WebCore/platform/graphics/GraphicsContext.cpp b/Source/WebCore/platform/graphics/GraphicsContext.cpp
>index 0dc0557b0d4f072edb98bc58c129b421a808f06d..210bbac327152300319280938153d162a739c2d3 100644
>--- a/Source/WebCore/platform/graphics/GraphicsContext.cpp
>+++ b/Source/WebCore/platform/graphics/GraphicsContext.cpp
>@@ -812,6 +812,9 @@ void GraphicsContext::drawImageBuffer(ImageBuffer& image, const FloatRect& desti
>     if (paintingDisabled())
>         return;
> 
>+    if (m_impl && m_impl->drawImageBuffer(image, destination, source, options))
>+        return;
>+
>     InterpolationQualityMaintainer interpolationQualityForThisScope(*this, options.interpolationQuality());
>     image.draw(*this, destination, source, options);
> }
>diff --git a/Source/WebCore/platform/graphics/GraphicsContextImpl.h b/Source/WebCore/platform/graphics/GraphicsContextImpl.h
>index c2cafe336cc56995dc40ded40167e683b42a57f7..3536d2f3b73cd488e98ec2e9fde248f8238c39ce 100644
>--- a/Source/WebCore/platform/graphics/GraphicsContextImpl.h
>+++ b/Source/WebCore/platform/graphics/GraphicsContextImpl.h
>@@ -73,6 +73,7 @@ public:
>     virtual ImageDrawResult drawTiledImage(Image&, const FloatRect& destination, const FloatPoint& source, const FloatSize& tileSize, const FloatSize& spacing, const ImagePaintingOptions&) = 0;
>     virtual ImageDrawResult drawTiledImage(Image&, const FloatRect& destination, const FloatRect& source, const FloatSize& tileScaleFactor, Image::TileRule hRule, Image::TileRule vRule, const ImagePaintingOptions&) = 0;
> 
>+    virtual bool drawImageBuffer(ImageBuffer&, const FloatRect& destination, const FloatRect& source, const ImagePaintingOptions&) = 0;
>     virtual void drawNativeImage(const NativeImagePtr&, const FloatSize& selfSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions&) = 0;
>     virtual void drawPattern(Image&, const FloatRect& destRect, const FloatRect& srcRect, const AffineTransform&, const FloatPoint& phase, const FloatSize& spacing, const ImagePaintingOptions&) = 0;
> 
>diff --git a/Source/WebCore/platform/graphics/ImageBuffer.h b/Source/WebCore/platform/graphics/ImageBuffer.h
>index 0ae9fcbd0588d4c4e1ef5af3cc7f12b612bf78da..8b94f91d9ba9146244f01b703cb347a8a9d7d198 100644
>--- a/Source/WebCore/platform/graphics/ImageBuffer.h
>+++ b/Source/WebCore/platform/graphics/ImageBuffer.h
>@@ -28,6 +28,7 @@
> #pragma once
> 
> #include "ImageBufferBackend.h"
>+#include "RemoteResourceIdentifier.h"
> #include "RenderingMode.h"
> 
> namespace WebCore {
>@@ -60,6 +61,9 @@ public:
>     
>     WEBCORE_EXPORT virtual ~ImageBuffer() = default;
> 
>+    virtual bool isAccelerated() const = 0;
>+    virtual RemoteResourceIdentifier remoteResourceIdentifier() const { return { }; }
>+    
>     virtual GraphicsContext& context() const = 0;
>     virtual void flushContext() = 0;
> 
>@@ -104,8 +108,6 @@ public:
>     virtual bool copyToPlatformTexture(GraphicsContextGLOpenGL&, GCGLenum, PlatformGLObject, GCGLenum, bool, bool) const = 0;
>     virtual PlatformLayer* platformLayer() const = 0;
>     
>-    virtual bool isAccelerated() const = 0;
>-
> protected:
>     ImageBuffer() = default;
> 
>diff --git a/Source/WebCore/platform/graphics/ImageBufferBackend.h b/Source/WebCore/platform/graphics/ImageBufferBackend.h
>index 58fc14836d92aa20019f20feedc5571e9ab5e95c..cb5872567f0883b5bd02e0eecb8cefdbe710a8ec 100644
>--- a/Source/WebCore/platform/graphics/ImageBufferBackend.h
>+++ b/Source/WebCore/platform/graphics/ImageBufferBackend.h
>@@ -101,7 +101,7 @@ public:
>     virtual bool copyToPlatformTexture(GraphicsContextGLOpenGL&, GCGLenum, PlatformGLObject, GCGLenum, bool, bool) const { return false; }
>     
>     static constexpr bool isOriginAtUpperLeftCorner = false;
>-    virtual bool isAccelerated() const { return false; }
>+    static constexpr bool isAccelerated = false;
> 
> protected:
>     WEBCORE_EXPORT ImageBufferBackend(const FloatSize& logicalSize, const IntSize& backendSize, float resolutionScale, ColorSpace);
>diff --git a/Source/WebCore/platform/graphics/RemoteResourceIdentifier.h b/Source/WebCore/platform/graphics/RemoteResourceIdentifier.h
>index 2af542dfec847abc371aa2f1e8e4b8dd9fb110e5..6690becdc8b4aae8524b3f6810fb9264c85c499c 100644
>--- a/Source/WebCore/platform/graphics/RemoteResourceIdentifier.h
>+++ b/Source/WebCore/platform/graphics/RemoteResourceIdentifier.h
>@@ -25,8 +25,6 @@
> 
> #pragma once
> 
>-#if ENABLE(GPU_PROCESS)
>-
> #include <wtf/ObjectIdentifier.h>
> 
> namespace WebCore {
>@@ -35,5 +33,3 @@ enum RemoteResourceIdentifierType { };
> using RemoteResourceIdentifier = ObjectIdentifier<RemoteResourceIdentifierType>;
> 
> } // namespace WebCore
>-
>-#endif // ENABLE(GPU_PROCESS)
>diff --git a/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.cpp b/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.cpp
>index b65b4d64406beb76c409d3e8c654975ca9f7eb63..8ef4f786b7249142456eff1f0ad8216cc9055367 100644
>--- a/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.cpp
>+++ b/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.cpp
>@@ -279,6 +279,12 @@ ImageDrawResult GraphicsContextImplCairo::drawTiledImage(Image& image, const Flo
>     return GraphicsContextImpl::drawTiledImageImpl(graphicsContext(), image, destination, source, tileScaleFactor, hRule, vRule, imagePaintingOptions);
> }
> 
>+bool GraphicsContextImplCairo::drawImageBuffer(ImageBuffer&, const FloatRect&, const FloatRect&, const ImagePaintingOptions&)
>+{
>+    // FIXME: Not implemented.
>+    return false;
>+}
>+
> void GraphicsContextImplCairo::drawNativeImage(const NativeImagePtr& image, const FloatSize& imageSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
> {
>     UNUSED_PARAM(imageSize);
>diff --git a/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.h b/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.h
>index e5e20748c6d7620f10cf2156628ef7e0be601c7b..2858fc22fc1fb99262b46054ac46f92b6ce9f0d2 100644
>--- a/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.h
>+++ b/Source/WebCore/platform/graphics/cairo/GraphicsContextImplCairo.h
>@@ -74,6 +74,8 @@ public:
>     ImageDrawResult drawImage(Image&, const FloatRect&, const FloatRect&, const ImagePaintingOptions&) override;
>     ImageDrawResult drawTiledImage(Image&, const FloatRect&, const FloatPoint&, const FloatSize&, const FloatSize&, const ImagePaintingOptions&) override;
>     ImageDrawResult drawTiledImage(Image&, const FloatRect&, const FloatRect&, const FloatSize&, Image::TileRule, Image::TileRule, const ImagePaintingOptions&) override;
>+
>+    bool drawImageBuffer(ImageBuffer&, const FloatRect&, const FloatRect&, const ImagePaintingOptions&) override;
>     void drawNativeImage(const NativeImagePtr&, const FloatSize&, const FloatRect&, const FloatRect&, const ImagePaintingOptions&) override;
>     void drawPattern(Image&, const FloatRect&, const FloatRect&, const AffineTransform&, const FloatPoint&, const FloatSize&, const ImagePaintingOptions&) override;
> 
>diff --git a/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.cpp b/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.cpp
>index c8065a9ec2514644f7405f9a5413f62235627154..dbc3b7eb8b3d1ad88d0ab3f0eef90a7c8d85e030 100644
>--- a/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.cpp
>+++ b/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.cpp
>@@ -190,11 +190,6 @@ IOSurface* ImageBufferIOSurfaceBackend::surface()
>     return m_surface.get();
> }
> 
>-bool ImageBufferIOSurfaceBackend::isAccelerated() const
>-{
>-    return true;
>-}
>-
> } // namespace WebCore
> 
> #endif // HAVE(IOSURFACE)
>diff --git a/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.h b/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.h
>index 2418f1d45d53d45933b3904a288c6101f14bcc31..323094ea795c5d2483c884403124a9040cc740fb 100644
>--- a/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.h
>+++ b/Source/WebCore/platform/graphics/cg/ImageBufferIOSurfaceBackend.h
>@@ -62,9 +62,9 @@ public:
>     RefPtr<ImageData> getImageData(AlphaPremultiplication outputFormat, const IntRect&) const override;
>     void putImageData(AlphaPremultiplication inputFormat, const ImageData&, const IntRect& srcRect, const IntPoint& destPoint, AlphaPremultiplication destFormat) override;
>     IOSurface* surface();
>-    bool isAccelerated() const override;
> 
>     static constexpr bool isOriginAtUpperLeftCorner = true;
>+    static constexpr bool isAccelerated = true;
> 
> protected:
>     static RetainPtr<CGColorSpaceRef> contextColorSpace(const GraphicsContext&);
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayList.h b/Source/WebCore/platform/graphics/displaylists/DisplayList.h
>index 506dabab0b8b4b731476bdf9f3095672b912ef19..322ecc1c1c415cef059fccfbaf508f93a59212ac 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayList.h
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayList.h
>@@ -64,6 +64,7 @@ enum class ItemType : uint8_t {
>     DrawImage,
>     DrawTiledImage,
>     DrawTiledScaledImage,
>+    DrawImageBuffer,
>     DrawNativeImage,
>     DrawPattern,
>     DrawRect,
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.cpp b/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.cpp
>index 23cc07e8ae442bdcea0d3674a5a8551c65cfdc87..d4617d3516f4f3e51d75d64434a6a39457a0001f 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.cpp
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.cpp
>@@ -33,9 +33,9 @@
> namespace WebCore {
> namespace DisplayList {
> 
>-DrawingContext::DrawingContext(const FloatSize& logicalSize, const AffineTransform& initialCTM, Recorder::Observer* observer)
>+DrawingContext::DrawingContext(const FloatSize& logicalSize, const AffineTransform& initialCTM, Recorder::Delegate* delegate)
>     : m_context([&](GraphicsContext& displayListContext) {
>-        return makeUnique<Recorder>(displayListContext, m_displayList, GraphicsContextState(), FloatRect({ }, logicalSize), initialCTM, observer);
>+        return makeUnique<Recorder>(displayListContext, m_displayList, GraphicsContextState(), FloatRect({ }, logicalSize), initialCTM, delegate);
>     })
> {
> }
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.h b/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.h
>index 7b673f32ad815a50081b7e7ab108131717fde543..22ed256e80ad293a052069b743088a1351f47cc0 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.h
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListDrawingContext.h
>@@ -35,7 +35,7 @@ namespace DisplayList {
> class DrawingContext {
>     WTF_MAKE_FAST_ALLOCATED;
> public:
>-    WEBCORE_EXPORT DrawingContext(const FloatSize& logicalSize, const AffineTransform& initialCTM = { }, Recorder::Observer* = nullptr);
>+    WEBCORE_EXPORT DrawingContext(const FloatSize& logicalSize, const AffineTransform& initialCTM = { }, Recorder::Delegate* = nullptr);
> 
>     GraphicsContext& context() const { return const_cast<DrawingContext&>(*this).m_context; }
>     WEBCORE_EXPORT Recorder& recorder();
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListImageBuffer.h b/Source/WebCore/platform/graphics/displaylists/DisplayListImageBuffer.h
>index 6fd912dfb8fe11c098dd6126a8c878ac6ba7ae02..32599e062d7cf59d1dc2ead01e760d66e3f7ec3c 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListImageBuffer.h
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListImageBuffer.h
>@@ -32,7 +32,7 @@ namespace WebCore {
> namespace DisplayList {
> 
> template<typename BackendType>
>-class ImageBuffer : public ConcreteImageBuffer<BackendType>, public Recorder::Observer {
>+class ImageBuffer : public ConcreteImageBuffer<BackendType> {
>     using BaseConcreteImageBuffer = ConcreteImageBuffer<BackendType>;
> 
> public:
>@@ -48,12 +48,12 @@ public:
> 
>     ImageBuffer(std::unique_ptr<BackendType>&& dataBackend, const FloatSize& size)
>         : BaseConcreteImageBuffer(WTFMove(dataBackend))
>-        , m_drawingContext(size, initialDrawingContextCTM(size), this)
>+        , m_drawingContext(size, initialDrawingContextCTM(size))
>     {
>     }
> 
>-    ImageBuffer(const FloatSize& size)
>-        : m_drawingContext(size, initialDrawingContextCTM(size), this)
>+    ImageBuffer(const FloatSize& size, Recorder::Delegate* delegate = nullptr)
>+        : m_drawingContext(size, initialDrawingContextCTM(size), delegate)
>     {
>     }
> 
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListItems.cpp b/Source/WebCore/platform/graphics/displaylists/DisplayListItems.cpp
>index 8d8b28193875c3166f81ed08e3d929961f7b8716..cf8892125610a8e3fb1226b24aaf2972dbb32405 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListItems.cpp
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListItems.cpp
>@@ -110,6 +110,8 @@ size_t Item::sizeInBytes(const Item& item)
>         return sizeof(downcast<DrawTiledImage>(item));
>     case ItemType::DrawTiledScaledImage:
>         return sizeof(downcast<DrawTiledScaledImage>(item));
>+    case ItemType::DrawImageBuffer:
>+        return sizeof(downcast<DrawImageBuffer>(item));
>     case ItemType::DrawNativeImage:
>         return sizeof(downcast<DrawNativeImage>(item));
>     case ItemType::DrawPattern:
>@@ -738,6 +740,32 @@ static TextStream& operator<<(TextStream& ts, const DrawTiledScaledImage& item)
>     return ts;
> }
> 
>+DrawImageBuffer::DrawImageBuffer(RemoteResourceIdentifier remoteResourceIdentifier, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
>+    : DrawingItem(ItemType::DrawImageBuffer)
>+    , m_remoteResourceIdentifier(remoteResourceIdentifier)
>+    , m_destinationRect(destRect)
>+    , m_srcRect(srcRect)
>+    , m_options(options)
>+{
>+}
>+
>+DrawImageBuffer::~DrawImageBuffer() = default;
>+
>+void DrawImageBuffer::apply(GraphicsContext&) const
>+{
>+    // Should be handled by the delegate.
>+    ASSERT_NOT_REACHED();
>+}
>+
>+static TextStream& operator<<(TextStream& ts, const DrawImageBuffer& item)
>+{
>+    ts << static_cast<const DrawingItem&>(item);
>+    ts.dumpProperty("remote-resource-identifier", item.remoteResourceIdentifier());
>+    ts.dumpProperty("source-rect", item.source());
>+    ts.dumpProperty("dest-rect", item.destinationRect());
>+    return ts;
>+}
>+
> DrawNativeImage::DrawNativeImage(const NativeImagePtr& image, const FloatSize& imageSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
>     : DrawingItem(ItemType::DrawNativeImage)
>     , m_image(image)
>@@ -1496,6 +1524,7 @@ static TextStream& operator<<(TextStream& ts, const ItemType& type)
>     case ItemType::DrawImage: ts << "draw-image"; break;
>     case ItemType::DrawTiledImage: ts << "draw-tiled-image"; break;
>     case ItemType::DrawTiledScaledImage: ts << "draw-tiled-scaled-image"; break;
>+    case ItemType::DrawImageBuffer: ts << "draw-image-buffer"; break;
>     case ItemType::DrawNativeImage: ts << "draw-native-image"; break;
>     case ItemType::DrawPattern: ts << "draw-pattern"; break;
>     case ItemType::DrawRect: ts << "draw-rect"; break;
>@@ -1602,6 +1631,9 @@ TextStream& operator<<(TextStream& ts, const Item& item)
>     case ItemType::DrawTiledScaledImage:
>         ts << downcast<DrawTiledScaledImage>(item);
>         break;
>+    case ItemType::DrawImageBuffer:
>+        ts << downcast<DrawImageBuffer>(item);
>+        break;
>     case ItemType::DrawNativeImage:
>         ts << downcast<DrawNativeImage>(item);
>         break;
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListItems.h b/Source/WebCore/platform/graphics/displaylists/DisplayListItems.h
>index d4ca98e648451b26cbf649835b1da2f3c23b4aff..6c3ec282505e5c306f110017be276d60950fe6d1 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListItems.h
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListItems.h
>@@ -35,6 +35,7 @@
> #include "ImageData.h"
> #include "MediaPlayerIdentifier.h"
> #include "Pattern.h"
>+#include "RemoteResourceIdentifier.h"
> #include "SharedBuffer.h"
> #include <wtf/TypeCasts.h>
> 
>@@ -1533,6 +1534,71 @@ Optional<Ref<DrawTiledScaledImage>> DrawTiledScaledImage::decode(Decoder& decode
>     return DrawTiledScaledImage::create(*imageHandle->image, *destination, *source, *tileScaleFactor, hRule, vRule, *imagePaintingOptions);
> }
> 
>+class DrawImageBuffer : public DrawingItem {
>+public:
>+    static Ref<DrawImageBuffer> create(RemoteResourceIdentifier remoteResourceIdentifier, const FloatRect& destination, const FloatRect& source, const ImagePaintingOptions& options)
>+    {
>+        return adoptRef(*new DrawImageBuffer(remoteResourceIdentifier, destination, source, options));
>+    }
>+
>+    WEBCORE_EXPORT virtual ~DrawImageBuffer();
>+
>+    RemoteResourceIdentifier remoteResourceIdentifier() const { return m_remoteResourceIdentifier; }
>+    FloatRect source() const { return m_srcRect; }
>+    FloatRect destinationRect() const { return m_destinationRect; }
>+    ImagePaintingOptions options() const { return m_options; }
>+
>+    template<class Encoder> void encode(Encoder&) const;
>+    template<class Decoder> static Optional<Ref<DrawImageBuffer>> decode(Decoder&);
>+
>+private:
>+    WEBCORE_EXPORT DrawImageBuffer(RemoteResourceIdentifier, const FloatRect& destination, const FloatRect& source, const ImagePaintingOptions&);
>+
>+    void apply(GraphicsContext&) const override;
>+
>+    Optional<FloatRect> localBounds(const GraphicsContext&) const override { return m_destinationRect; }
>+
>+    RemoteResourceIdentifier m_remoteResourceIdentifier;
>+    FloatRect m_destinationRect;
>+    FloatRect m_srcRect;
>+    ImagePaintingOptions m_options;
>+};
>+
>+template<class Encoder>
>+void DrawImageBuffer::encode(Encoder& encoder) const
>+{
>+    encoder << m_remoteResourceIdentifier;
>+    encoder << m_destinationRect;
>+    encoder << m_srcRect;
>+    encoder << m_options;
>+}
>+
>+template<class Decoder>
>+Optional<Ref<DrawImageBuffer>> DrawImageBuffer::decode(Decoder& decoder)
>+{
>+    Optional<RemoteResourceIdentifier> remoteResourceIdentifier;
>+    decoder >> remoteResourceIdentifier;
>+    if (!remoteResourceIdentifier)
>+        return WTF::nullopt;
>+
>+    Optional<FloatRect> destination;
>+    decoder >> destination;
>+    if (!destination)
>+        return WTF::nullopt;
>+
>+    Optional<FloatRect> source;
>+    decoder >> source;
>+    if (!source)
>+        return WTF::nullopt;
>+
>+    Optional<ImagePaintingOptions> options;
>+    decoder >> options;
>+    if (!options)
>+        return WTF::nullopt;
>+
>+    return DrawImageBuffer::create(*remoteResourceIdentifier, *destination, *source, *options);
>+}
>+
> class DrawNativeImage : public DrawingItem {
> public:
>     static Ref<DrawNativeImage> create(const NativeImagePtr& image, const FloatSize& imageSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
>@@ -3066,6 +3132,9 @@ void Item::encode(Encoder& encoder) const
>     case ItemType::DrawTiledScaledImage:
>         encoder << downcast<DrawTiledScaledImage>(*this);
>         break;
>+    case ItemType::DrawImageBuffer:
>+        encoder << downcast<DrawImageBuffer>(*this);
>+        break;
>     case ItemType::DrawNativeImage:
>         encoder << downcast<DrawNativeImage>(*this);
>         break;
>@@ -3263,6 +3332,10 @@ Optional<Ref<Item>> Item::decode(Decoder& decoder)
>         if (auto item = DrawTiledScaledImage::decode(decoder))
>             return static_reference_cast<Item>(WTFMove(*item));
>         break;
>+    case ItemType::DrawImageBuffer:
>+        if (auto item = DrawImageBuffer::decode(decoder))
>+            return static_reference_cast<Item>(WTFMove(*item));
>+        break;
>     case ItemType::DrawNativeImage:
>         if (auto item = DrawNativeImage::decode(decoder))
>             return static_reference_cast<Item>(WTFMove(*item));
>@@ -3425,6 +3498,7 @@ SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawGlyphs)
> SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawImage)
> SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawTiledImage)
> SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawTiledScaledImage)
>+SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawImageBuffer)
> SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawNativeImage)
> SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawPattern)
> SPECIALIZE_TYPE_TRAITS_DISPLAYLIST_ITEM(DrawRect)
>@@ -3487,6 +3561,7 @@ template<> struct EnumTraits<WebCore::DisplayList::ItemType> {
>     WebCore::DisplayList::ItemType::DrawImage,
>     WebCore::DisplayList::ItemType::DrawTiledImage,
>     WebCore::DisplayList::ItemType::DrawTiledScaledImage,
>+    WebCore::DisplayList::ItemType::DrawImageBuffer,
>     WebCore::DisplayList::ItemType::DrawNativeImage,
>     WebCore::DisplayList::ItemType::DrawPattern,
>     WebCore::DisplayList::ItemType::DrawRect,
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.cpp b/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.cpp
>index 68d2f680515eae558a0d4fbef6ab1a27e0a09eb4..8b71a655b2e2337d8ec2d074db5fcaa3ed689294 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.cpp
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.cpp
>@@ -30,6 +30,7 @@
> #include "DisplayListDrawingContext.h"
> #include "DisplayListItems.h"
> #include "GraphicsContext.h"
>+#include "ImageBuffer.h"
> #include "Logging.h"
> #include <wtf/MathExtras.h>
> #include <wtf/text/TextStream.h>
>@@ -37,10 +38,10 @@
> namespace WebCore {
> namespace DisplayList {
> 
>-Recorder::Recorder(GraphicsContext& context, DisplayList& displayList, const GraphicsContextState& state, const FloatRect& initialClip, const AffineTransform& initialCTM, Observer* observer)
>+Recorder::Recorder(GraphicsContext& context, DisplayList& displayList, const GraphicsContextState& state, const FloatRect& initialClip, const AffineTransform& initialCTM, Delegate* delegate)
>     : GraphicsContextImpl(context, initialClip, AffineTransform())
>     , m_displayList(displayList)
>-    , m_observer(observer)
>+    , m_delegate(delegate)
> {
>     LOG_WITH_STREAM(DisplayLists, stream << "\nRecording with clip " << initialClip);
>     m_stateStack.append({ state, initialCTM, initialClip });
>@@ -93,8 +94,8 @@ static Ref<Item> createStateChangeItem(const GraphicsContextStateChange& changes
> 
> void Recorder::willAppendItem(const Item& item)
> {
>-    if (m_observer)
>-        m_observer->willAppendItem(item);
>+    if (m_delegate)
>+        m_delegate->willAppendItem(item);
> 
>     if (item.isDrawingItem()
> #if USE(CG)
>@@ -166,6 +167,15 @@ ImageDrawResult Recorder::drawTiledImage(Image& image, const FloatRect& destinat
>     return ImageDrawResult::DidRecord;
> }
> 
>+bool Recorder::drawImageBuffer(WebCore::ImageBuffer& imageBuffer, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
>+{
>+    if (!m_delegate || !m_delegate->lockRemoteImageBuffer(imageBuffer))
>+        return false;
>+
>+    appendItemAndUpdateExtent(DrawImageBuffer::create(imageBuffer.remoteResourceIdentifier(), destRect, srcRect, options));
>+    return true;
>+}
>+
> void Recorder::drawNativeImage(const NativeImagePtr& image, const FloatSize& imageSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
> {
>     appendItemAndUpdateExtent(DrawNativeImage::create(image, imageSize, destRect, srcRect, options));
>diff --git a/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.h b/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.h
>index 1b24c26c67288f817273a2d2aef2b4bc96e35c75..923c54885729fb53776dadad9a68bd513287b312 100644
>--- a/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.h
>+++ b/Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.h
>@@ -53,8 +53,8 @@ class Recorder : public GraphicsContextImpl {
>     WTF_MAKE_FAST_ALLOCATED;
>     WTF_MAKE_NONCOPYABLE(Recorder);
> public:
>-    class Observer;
>-    WEBCORE_EXPORT Recorder(GraphicsContext&, DisplayList&, const GraphicsContextState&, const FloatRect& initialClip, const AffineTransform&, Observer* = nullptr);
>+    class Delegate;
>+    WEBCORE_EXPORT Recorder(GraphicsContext&, DisplayList&, const GraphicsContextState&, const FloatRect& initialClip, const AffineTransform&, Delegate* = nullptr);
>     WEBCORE_EXPORT virtual ~Recorder();
> 
>     WEBCORE_EXPORT void putImageData(AlphaPremultiplication inputFormat, const ImageData&, const IntRect& srcRect, const IntPoint& destPoint, AlphaPremultiplication destFormat);
>@@ -63,10 +63,11 @@ public:
> 
>     void appendItemAndUpdateExtent(Ref<DrawingItem>&&);
> 
>-    class Observer {
>+    class Delegate {
>     public:
>-        virtual ~Observer() { }
>+        virtual ~Delegate() { }
>         virtual void willAppendItem(const Item&) { };
>+        virtual bool lockRemoteImageBuffer(WebCore::ImageBuffer&) { return false; }
>     };
> 
> private:
>@@ -105,6 +106,7 @@ private:
>     ImageDrawResult drawTiledImage(Image&, const FloatRect& destination, const FloatPoint& source, const FloatSize& tileSize, const FloatSize& spacing, const ImagePaintingOptions&) override;
>     ImageDrawResult drawTiledImage(Image&, const FloatRect& destination, const FloatRect& source, const FloatSize& tileScaleFactor, Image::TileRule hRule, Image::TileRule vRule, const ImagePaintingOptions&) override;
> 
>+    bool drawImageBuffer(WebCore::ImageBuffer&, const FloatRect& destination, const FloatRect& source, const ImagePaintingOptions&) override;
>     void drawNativeImage(const NativeImagePtr&, const FloatSize& selfSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions&) override;
>     void drawPattern(Image&, const FloatRect& destRect, const FloatRect& srcRect, const AffineTransform&, const FloatPoint& phase, const FloatSize& spacing, const ImagePaintingOptions&) override;
> 
>@@ -187,7 +189,7 @@ private:
>     ContextState& currentState();
> 
>     DisplayList& m_displayList;
>-    Observer* m_observer;
>+    Delegate* m_delegate;
> 
>     Vector<ContextState, 32> m_stateStack;
> };
>diff --git a/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.cpp b/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.cpp
>index 304facbab1521791daa86db1531753e38671084d..a2c9e093fc14ba5c1e829c4b24e16540037a4455 100644
>--- a/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.cpp
>+++ b/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.cpp
>@@ -549,6 +549,12 @@ ImageDrawResult CairoOperationRecorder::drawTiledImage(Image& image, const Float
>     return GraphicsContextImpl::drawTiledImageImpl(graphicsContext(), image, destination, source, tileScaleFactor, hRule, vRule, imagePaintingOptions);
> }
> 
>+bool CairoOperationRecorder::drawImageBuffer(ImageBuffer&, const FloatRect&, const FloatRect&, const ImagePaintingOptions&)
>+{
>+    // FIXME: Not implemented.
>+    return false;
>+}
>+
> void CairoOperationRecorder::drawNativeImage(const NativeImagePtr& image, const FloatSize& imageSize, const FloatRect& destRect, const FloatRect& srcRect, const ImagePaintingOptions& options)
> {
>     struct DrawNativeImage final : PaintingOperation, OperationData<RefPtr<cairo_surface_t>, FloatRect, FloatRect, ImagePaintingOptions, float, Cairo::ShadowState> {
>diff --git a/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.h b/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.h
>index 572ff2166f6e973a763b67cb6bb96f43f26a8d50..38093d4135b4d7b6511a16087aff13f603ed13ba 100644
>--- a/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.h
>+++ b/Source/WebCore/platform/graphics/nicosia/cairo/NicosiaCairoOperationRecorder.h
>@@ -67,6 +67,8 @@ private:
>     WebCore::ImageDrawResult drawImage(WebCore::Image&, const WebCore::FloatRect&, const WebCore::FloatRect&, const WebCore::ImagePaintingOptions&) override;
>     WebCore::ImageDrawResult drawTiledImage(WebCore::Image&, const WebCore::FloatRect&, const WebCore::FloatPoint&, const WebCore::FloatSize&, const WebCore::FloatSize&, const WebCore::ImagePaintingOptions&) override;
>     WebCore::ImageDrawResult drawTiledImage(WebCore::Image&, const WebCore::FloatRect&, const WebCore::FloatRect&, const WebCore::FloatSize&, WebCore::Image::TileRule, WebCore::Image::TileRule, const WebCore::ImagePaintingOptions&) override;
>+
>+    bool drawImageBuffer(WebCore::ImageBuffer&, const WebCore::FloatRect& destination, const WebCore::FloatRect& source, const WebCore::ImagePaintingOptions&) override;
>     void drawNativeImage(const WebCore::NativeImagePtr&, const WebCore::FloatSize&, const WebCore::FloatRect&, const WebCore::FloatRect&, const WebCore::ImagePaintingOptions&) override;
>     void drawPattern(WebCore::Image&, const WebCore::FloatRect&, const WebCore::FloatRect&, const WebCore::AffineTransform&, const WebCore::FloatPoint&, const WebCore::FloatSize&, const WebCore::ImagePaintingOptions&) override;
> 
>diff --git a/Source/WebKit/GPUProcess/graphics/RemoteImageBuffer.h b/Source/WebKit/GPUProcess/graphics/RemoteImageBuffer.h
>index 78d82f8c44bc37d213a80884abe84fcf02a04f2b..e268362a514bfb0d930df24c27fab989867f9be3 100644
>--- a/Source/WebKit/GPUProcess/graphics/RemoteImageBuffer.h
>+++ b/Source/WebKit/GPUProcess/graphics/RemoteImageBuffer.h
>@@ -83,7 +83,7 @@ private:
>             return true;
>         }
> 
>-        return false;
>+        return m_remoteRenderingBackend.applyResourceItem(item, context);
>     }
> 
>     void apply(WebCore::DisplayList::PaintFrameForMedia& item, WebCore::GraphicsContext& context)
>diff --git a/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.cpp b/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.cpp
>index 1ef28ee2f2521dca554f480502f7274c9cc29b38..653912ae4af82753667f9389e4b5748332d16e22 100644
>--- a/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.cpp
>+++ b/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.cpp
>@@ -72,6 +72,18 @@ uint64_t RemoteRenderingBackend::messageSenderDestinationID() const
>     return m_renderingBackendIdentifier.toUInt64();
> }
> 
>+bool RemoteRenderingBackend::applyResourceItem(const DisplayList::Item& item, GraphicsContext& context)
>+{
>+    if (item.type() == DisplayList::ItemType::DrawImageBuffer) {
>+        auto& drawItem = static_cast<const DisplayList::DrawImageBuffer&>(item);
>+        if (auto imageBuffer = m_remoteResourceCache.cachedImageBuffer(drawItem.remoteResourceIdentifier())) {
>+            imageBuffer->draw(context, drawItem.destinationRect(), drawItem.source(), drawItem.options());
>+            return true;
>+        }
>+    }
>+    return false;
>+}
>+
> void RemoteRenderingBackend::imageBufferBackendWasCreated(const FloatSize& logicalSize, const IntSize& backendSize, float resolutionScale, ColorSpace colorSpace, ImageBufferBackendHandle handle, RemoteResourceIdentifier remoteResourceIdentifier)
> {
>     send(Messages::RemoteRenderingBackendProxy::ImageBufferBackendWasCreated(logicalSize, backendSize, resolutionScale, colorSpace, WTFMove(handle), remoteResourceIdentifier), m_renderingBackendIdentifier);
>diff --git a/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.h b/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.h
>index effba449b188ea2b54d362c2ac54c28fc0ccb3ed..81874fae65d26182a801244372efcb06f189fd08 100644
>--- a/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.h
>+++ b/Source/WebKit/GPUProcess/graphics/RemoteRenderingBackend.h
>@@ -42,6 +42,7 @@
> namespace WebCore {
> namespace DisplayList {
> class DisplayList;
>+class Item;
> }
> class FloatSize;
> enum class ColorSpace : uint8_t;
>@@ -61,6 +62,9 @@ public:
> 
>     GPUConnectionToWebProcess* gpuConnectionToWebProcess() const;
> 
>+    // Rendering operations.
>+    bool applyResourceItem(const WebCore::DisplayList::Item&, WebCore::GraphicsContext&);
>+
>     // Messages to be sent.
>     void imageBufferBackendWasCreated(const WebCore::FloatSize& logicalSize, const WebCore::IntSize& backendSize, float resolutionScale, WebCore::ColorSpace, ImageBufferBackendHandle, WebCore::RemoteResourceIdentifier);
>     void flushDisplayListWasCommitted(DisplayListFlushIdentifier, WebCore::RemoteResourceIdentifier);
>diff --git a/Source/WebKit/Sources.txt b/Source/WebKit/Sources.txt
>index 796db6996eedfe5b7e928001372054cf69c38046..7a3b2300b7c36890ffc253bba0554af20362f5d5 100644
>--- a/Source/WebKit/Sources.txt
>+++ b/Source/WebKit/Sources.txt
>@@ -557,8 +557,8 @@ WebProcess/MediaStream/UserMediaPermissionRequestManager.cpp
> 
> WebProcess/GPU/GPUProcessConnection.cpp
> WebProcess/GPU/graphics/ImageBufferShareableBitmapBackend.cpp
>-WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.cpp
> WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp
>+WebProcess/GPU/graphics/RemoteResourceCacheProxy.cpp
> WebProcess/GPU/media/AudioTrackPrivateRemote.cpp
> WebProcess/GPU/media/MediaPlayerPrivateRemote.cpp
> WebProcess/GPU/media/RemoteAudioDestinationProxy.cpp
>diff --git a/Source/WebKit/WebKit.xcodeproj/project.pbxproj b/Source/WebKit/WebKit.xcodeproj/project.pbxproj
>index 6bd9ac45f31ac43c2fc0964af5fdde4a78e68487..7486903488ca63a154a1e9c016e58fcc8e8bea89 100644
>--- a/Source/WebKit/WebKit.xcodeproj/project.pbxproj
>+++ b/Source/WebKit/WebKit.xcodeproj/project.pbxproj
>@@ -4224,8 +4224,6 @@
> 		71A676A522C62318007D6295 /* WKTouchActionGestureRecognizer.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = WKTouchActionGestureRecognizer.mm; path = ios/WKTouchActionGestureRecognizer.mm; sourceTree = "<group>"; };
> 		71FB810A2260627A00323677 /* WebsiteSimulatedMouseEventsDispatchPolicy.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WebsiteSimulatedMouseEventsDispatchPolicy.h; sourceTree = "<group>"; };
> 		7227800B2408BD7D007D376B /* PlatformRemoteImageBufferProxy.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = PlatformRemoteImageBufferProxy.h; sourceTree = "<group>"; };
>-		7227800C24097A02007D376B /* RemoteImageBufferMessageHandlerProxy.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = RemoteImageBufferMessageHandlerProxy.cpp; sourceTree = "<group>"; };
>-		7227800D24097A02007D376B /* RemoteImageBufferMessageHandlerProxy.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RemoteImageBufferMessageHandlerProxy.h; sourceTree = "<group>"; };
> 		726D56DD253A64810002EF90 /* RemoteResourceCache.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = RemoteResourceCache.cpp; sourceTree = "<group>"; };
> 		726D56DE253A64810002EF90 /* RemoteResourceCache.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RemoteResourceCache.h; sourceTree = "<group>"; };
> 		727A7F342407857D004D2931 /* ImageBufferShareableIOSurfaceBackend.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ImageBufferShareableIOSurfaceBackend.cpp; sourceTree = "<group>"; };
>@@ -4237,6 +4235,8 @@
> 		727A7F492408AEE6004D2931 /* RemoteImageBufferProxy.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RemoteImageBufferProxy.h; sourceTree = "<group>"; };
> 		728E86EF1795188C0087879E /* WebColorPickerMac.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WebColorPickerMac.h; sourceTree = "<group>"; };
> 		728E86F01795188C0087879E /* WebColorPickerMac.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = WebColorPickerMac.mm; sourceTree = "<group>"; };
>+		72B53157253C1E4D0049295A /* RemoteResourceCacheProxy.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = RemoteResourceCacheProxy.cpp; sourceTree = "<group>"; };
>+		72B53158253C1E4D0049295A /* RemoteResourceCacheProxy.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = RemoteResourceCacheProxy.h; sourceTree = "<group>"; };
> 		75A8D2C4187CCF9F00C39C9E /* WKWebsiteDataStore.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WKWebsiteDataStore.h; sourceTree = "<group>"; };
> 		75A8D2C5187CCF9F00C39C9E /* WKWebsiteDataStore.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = WKWebsiteDataStore.mm; sourceTree = "<group>"; };
> 		75A8D2D4187D1C0100C39C9E /* WKWebsiteDataStoreInternal.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WKWebsiteDataStoreInternal.h; sourceTree = "<group>"; };
>@@ -8138,12 +8138,12 @@
> 				727A7F36240788F0004D2931 /* ImageBufferShareableBitmapBackend.h */,
> 				727A7F38240788F0004D2931 /* PlatformImageBufferShareableBackend.h */,
> 				7227800B2408BD7D007D376B /* PlatformRemoteImageBufferProxy.h */,
>-				7227800C24097A02007D376B /* RemoteImageBufferMessageHandlerProxy.cpp */,
>-				7227800D24097A02007D376B /* RemoteImageBufferMessageHandlerProxy.h */,
> 				727A7F492408AEE6004D2931 /* RemoteImageBufferProxy.h */,
> 				5506409D2407160900AAE045 /* RemoteRenderingBackendProxy.cpp */,
> 				5506409E2407160900AAE045 /* RemoteRenderingBackendProxy.h */,
> 				550640A0240719E100AAE045 /* RemoteRenderingBackendProxy.messages.in */,
>+				72B53157253C1E4D0049295A /* RemoteResourceCacheProxy.cpp */,
>+				72B53158253C1E4D0049295A /* RemoteResourceCacheProxy.h */,
> 				5506409F2407196A00AAE045 /* RenderingBackendIdentifier.h */,
> 			);
> 			path = graphics;
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/PlatformRemoteImageBufferProxy.h b/Source/WebKit/WebProcess/GPU/graphics/PlatformRemoteImageBufferProxy.h
>index 9aff088e37ca76a7f864ae7e42bbb7004f1f1523..00060ec101c254e2b58a7646a4a424f3d02449e3 100644
>--- a/Source/WebKit/WebProcess/GPU/graphics/PlatformRemoteImageBufferProxy.h
>+++ b/Source/WebKit/WebProcess/GPU/graphics/PlatformRemoteImageBufferProxy.h
>@@ -37,4 +37,14 @@ using AcceleratedRemoteImageBufferProxy = RemoteImageBufferProxy<AcceleratedImag
> 
> } // namespace WebKit
> 
>+SPECIALIZE_TYPE_TRAITS_BEGIN(WebKit::UnacceleratedRemoteImageBufferProxy)
>+    static bool isType(const WebCore::ImageBuffer& imageBuffer) { return imageBuffer.remoteResourceIdentifier() && !imageBuffer.isAccelerated(); }
>+SPECIALIZE_TYPE_TRAITS_END()
>+
>+#if HAVE(IOSURFACE)
>+SPECIALIZE_TYPE_TRAITS_BEGIN(WebKit::AcceleratedRemoteImageBufferProxy)
>+    static bool isType(const WebCore::ImageBuffer& imageBuffer) { return imageBuffer.remoteResourceIdentifier() && imageBuffer.isAccelerated(); }
>+SPECIALIZE_TYPE_TRAITS_END()
>+#endif
>+
> #endif // ENABLE(GPU_PROCESS)
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.cpp b/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.cpp
>deleted file mode 100644
>index e9562a368e69e4230e7262c2636df286d746eac5..0000000000000000000000000000000000000000
>--- a/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.cpp
>+++ /dev/null
>@@ -1,103 +0,0 @@
>-/*
>- * Copyright (C) 2020 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 "RemoteImageBufferMessageHandlerProxy.h"
>-
>-#if ENABLE(GPU_PROCESS)
>-
>-#include "ImageDataReference.h"
>-#include "RemoteRenderingBackendMessages.h"
>-#include "RemoteRenderingBackendProxy.h"
>-#include <WebCore/DisplayListItems.h>
>-#include <wtf/SystemTracing.h>
>-
>-namespace WebKit {
>-using namespace WebCore;
>-
>-RemoteImageBufferMessageHandlerProxy::RemoteImageBufferMessageHandlerProxy(const FloatSize& size, RenderingMode renderingMode, float resolutionScale, ColorSpace colorSpace, RemoteRenderingBackendProxy& remoteRenderingBackendProxy)
>-    : m_remoteRenderingBackendProxy(makeWeakPtr(remoteRenderingBackendProxy))
>-{
>-    // Create the RemoteImageBufferProxy.
>-    m_remoteRenderingBackendProxy->send(Messages::RemoteRenderingBackend::CreateImageBuffer(size, renderingMode, resolutionScale, colorSpace, m_remoteResourceIdentifier), m_remoteRenderingBackendProxy->renderingBackendIdentifier());
>-}
>-
>-RemoteImageBufferMessageHandlerProxy::~RemoteImageBufferMessageHandlerProxy()
>-{
>-    // Release the RemoteImageBufferProxy.
>-    if (!m_remoteRenderingBackendProxy)
>-        return;
>-    m_remoteRenderingBackendProxy->send(Messages::RemoteRenderingBackend::ReleaseRemoteResource(m_remoteResourceIdentifier), m_remoteRenderingBackendProxy->renderingBackendIdentifier());
>-}
>-
>-RefPtr<ImageData> RemoteImageBufferMessageHandlerProxy::getImageData(AlphaPremultiplication outputFormat, const IntRect& srcRect) const
>-{
>-    IPC::ImageDataReference imageDataReference;
>-    m_remoteRenderingBackendProxy->sendSync(Messages::RemoteRenderingBackend::GetImageData(outputFormat, srcRect, m_remoteResourceIdentifier), Messages::RemoteRenderingBackend::GetImageData::Reply(imageDataReference), m_remoteRenderingBackendProxy->renderingBackendIdentifier(), 1_s);
>-    return imageDataReference.buffer();
>-}
>-
>-void RemoteImageBufferMessageHandlerProxy::waitForImageBufferBackendWasCreated()
>-{
>-    if (m_remoteRenderingBackendProxy && !isBackendCreated())
>-        m_remoteRenderingBackendProxy->waitForImageBufferBackendWasCreated();
>-}
>-
>-void RemoteImageBufferMessageHandlerProxy::waitForFlushDisplayListWasCommitted()
>-{
>-    if (m_remoteRenderingBackendProxy && isPendingFlush())
>-        m_remoteRenderingBackendProxy->waitForFlushDisplayListWasCommitted();
>-}
>-
>-void RemoteImageBufferMessageHandlerProxy::flushDisplayList(WebCore::DisplayList::DisplayList& displayList)
>-{
>-    if (!m_remoteRenderingBackendProxy)
>-        return;
>-    
>-    TraceScope tracingScope(FlushRemoteImageBufferStart, FlushRemoteImageBufferEnd);
>-    m_remoteRenderingBackendProxy->send(Messages::RemoteRenderingBackend::FlushDisplayList(displayList, m_remoteResourceIdentifier), m_remoteRenderingBackendProxy->renderingBackendIdentifier());
>-    displayList.clear();
>-}
>-
>-void RemoteImageBufferMessageHandlerProxy::flushDisplayListAndWaitCommit(WebCore::DisplayList::DisplayList& displayList)
>-{
>-    if (!m_remoteRenderingBackendProxy)
>-        return;
>-
>-    TraceScope tracingScope(FlushRemoteImageBufferStart, FlushRemoteImageBufferEnd, 1);
>-    m_sentFlushIdentifier = DisplayListFlushIdentifier::generate();
>-    m_remoteRenderingBackendProxy->send(Messages::RemoteRenderingBackend::FlushDisplayListAndCommit(displayList, m_sentFlushIdentifier, m_remoteResourceIdentifier), m_remoteRenderingBackendProxy->renderingBackendIdentifier());
>-    displayList.clear();
>-    waitForFlushDisplayListWasCommitted();
>-}
>-
>-void RemoteImageBufferMessageHandlerProxy::commitFlushContext(DisplayListFlushIdentifier flushIdentifier)
>-{
>-    m_receivedFlushIdentifier = flushIdentifier;
>-}
>-
>-} // namespace WebKit
>-
>-#endif // ENABLE(GPU_PROCESS)
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.h b/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.h
>deleted file mode 100644
>index b9a026a81298796e7bd35fa96eee904de4bfb5fd..0000000000000000000000000000000000000000
>--- a/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferMessageHandlerProxy.h
>+++ /dev/null
>@@ -1,83 +0,0 @@
>-/*
>- * Copyright (C) 2020 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. ``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
>- * 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
>-
>-#if ENABLE(GPU_PROCESS)
>-
>-#include "DisplayListFlushIdentifier.h"
>-#include "ImageBufferBackendHandle.h"
>-#include <WebCore/ColorSpace.h>
>-#include <WebCore/DisplayList.h>
>-#include <WebCore/FloatSize.h>
>-#include <WebCore/RemoteResourceIdentifier.h>
>-#include <WebCore/RenderingMode.h>
>-
>-namespace WebCore {
>-class ImageData;
>-enum class AlphaPremultiplication : uint8_t;
>-}
>-
>-namespace WebKit {
>-
>-class RemoteRenderingBackendProxy;
>-
>-class RemoteImageBufferMessageHandlerProxy {
>-public:
>-    virtual ~RemoteImageBufferMessageHandlerProxy();
>-
>-    WebCore::RemoteResourceIdentifier remoteResourceIdentifier() const { return m_remoteResourceIdentifier; }
>-
>-    // Messages to be received. See RemoteRenderingBackend.messages.in.
>-    virtual void createBackend(const WebCore::FloatSize& logicalSize, const WebCore::IntSize& backendSize, float resolutionScale, WebCore::ColorSpace, ImageBufferBackendHandle) = 0;
>-
>-    void commitFlushContext(DisplayListFlushIdentifier);
>-
>-protected:
>-    RemoteImageBufferMessageHandlerProxy(const WebCore::FloatSize&, WebCore::RenderingMode, float resolutionScale, WebCore::ColorSpace, RemoteRenderingBackendProxy&);
>-
>-    virtual bool isBackendCreated() const = 0;
>-    bool isPendingFlush() const { return m_sentFlushIdentifier != m_receivedFlushIdentifier; }
>-
>-    RefPtr<WebCore::ImageData> getImageData(WebCore::AlphaPremultiplication outputFormat, const WebCore::IntRect& srcRect) const;
>-
>-    void waitForImageBufferBackendWasCreated();
>-    void waitForFlushDisplayListWasCommitted();
>-
>-    // Messages to be sent. See RemoteRenderingBackendProxy.messages.in.
>-    void flushDisplayList(WebCore::DisplayList::DisplayList&);
>-    void flushDisplayListAndWaitCommit(WebCore::DisplayList::DisplayList&);
>-
>-private:
>-    WeakPtr<RemoteRenderingBackendProxy> m_remoteRenderingBackendProxy;
>-    WebCore::RemoteResourceIdentifier m_remoteResourceIdentifier { WebCore::RemoteResourceIdentifier::generate() };
>-
>-    DisplayListFlushIdentifier m_sentFlushIdentifier;
>-    DisplayListFlushIdentifier m_receivedFlushIdentifier;
>-};
>-
>-} // namespace WebKit
>-
>-#endif // ENABLE(GPU_PROCESS)
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferProxy.h b/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferProxy.h
>index 20fbf81c982552ef76bb6cd15dc3a1e9d3880ec3..e0d2ff7d1a66a1ce52a351f16f8455da7893d0c9 100644
>--- a/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferProxy.h
>+++ b/Source/WebKit/WebProcess/GPU/graphics/RemoteImageBufferProxy.h
>@@ -27,7 +27,6 @@
> 
> #if ENABLE(GPU_PROCESS)
> 
>-#include "RemoteImageBufferMessageHandlerProxy.h"
> #include <WebCore/DisplayListImageBuffer.h>
> #include <WebCore/DisplayListItems.h>
> #include <WebCore/DisplayListRecorder.h>
>@@ -37,54 +36,71 @@ namespace WebKit {
> class RemoteRenderingBackend;
> 
> template<typename BackendType>
>-class RemoteImageBufferProxy : public WebCore::DisplayList::ImageBuffer<BackendType>, public RemoteImageBufferMessageHandlerProxy {
>+class RemoteImageBufferProxy : public WebCore::DisplayList::ImageBuffer<BackendType>, public WebCore::DisplayList::Recorder::Delegate {
>     using BaseDisplayListImageBuffer = WebCore::DisplayList::ImageBuffer<BackendType>;
>     using BaseDisplayListImageBuffer::m_backend;
>     using BaseDisplayListImageBuffer::m_drawingContext;
> 
> public:
>-    static std::unique_ptr<RemoteImageBufferProxy> create(const WebCore::FloatSize& size, WebCore::RenderingMode renderingMode, float resolutionScale, WebCore::ColorSpace colorSpace, RemoteRenderingBackendProxy& remoteRenderingBackendProxy)
>+    static std::unique_ptr<RemoteImageBufferProxy> create(const WebCore::FloatSize& size, float resolutionScale, RemoteRenderingBackendProxy& remoteRenderingBackendProxy)
>     {
>         if (BackendType::calculateBackendSize(size, resolutionScale).isEmpty())
>             return nullptr;
> 
>-        return std::unique_ptr<RemoteImageBufferProxy>(new RemoteImageBufferProxy(size, renderingMode, resolutionScale, colorSpace, remoteRenderingBackendProxy));
>+        return std::unique_ptr<RemoteImageBufferProxy>(new RemoteImageBufferProxy(size, remoteRenderingBackendProxy));
>     }
> 
>     ~RemoteImageBufferProxy()
>     {
>+        if (!m_remoteRenderingBackendProxy)
>+            return;
>         flushDrawingContext();
>+        m_remoteRenderingBackendProxy->remoteResourceCacheProxy().releaseImageBuffer(m_remoteResourceIdentifier);
>     }
> 
>-protected:
>-    RemoteImageBufferProxy(const WebCore::FloatSize& size, WebCore::RenderingMode renderingMode, float resolutionScale, WebCore::ColorSpace colorSpace, RemoteRenderingBackendProxy& remoteRenderingBackendProxy)
>-        : BaseDisplayListImageBuffer(size)
>-        , RemoteImageBufferMessageHandlerProxy(size, renderingMode, resolutionScale, colorSpace, remoteRenderingBackendProxy)
>-    {
>-    }
>+    WebCore::RemoteResourceIdentifier remoteResourceIdentifier() const override { return m_remoteResourceIdentifier; }
> 
>-    void createBackend(const WebCore::FloatSize& logicalSize, const WebCore::IntSize& backendSize, float resolutionScale, WebCore::ColorSpace colorSpace, ImageBufferBackendHandle handle) override
>+    void createBackend(const WebCore::FloatSize& logicalSize, const WebCore::IntSize& backendSize, float resolutionScale, WebCore::ColorSpace colorSpace, ImageBufferBackendHandle handle)
>     {
>         ASSERT(!m_backend);
>         m_backend = BackendType::create(logicalSize, backendSize, resolutionScale, colorSpace, WTFMove(handle));
>     }
>-    
>-    bool isBackendCreated() const override { return m_backend.get(); }
>+
>+    void commitFlushDisplayList(DisplayListFlushIdentifier flushIdentifier)
>+    {
>+        m_receivedFlushIdentifier = flushIdentifier;
>+    }
>+
>+protected:
>+    RemoteImageBufferProxy(const WebCore::FloatSize& size, RemoteRenderingBackendProxy& remoteRenderingBackendProxy)
>+        : BaseDisplayListImageBuffer(size, this)
>+        , m_remoteRenderingBackendProxy(makeWeakPtr(remoteRenderingBackendProxy))
>+    {
>+        ASSERT(m_remoteRenderingBackendProxy);
>+    }
>+
>+    bool isPendingFlush() const { return m_sentFlushIdentifier != m_receivedFlushIdentifier; }
> 
>     BackendType* ensureBackendCreated() const override
>     {
>-        if (!m_backend)
>-            const_cast<RemoteImageBufferProxy&>(*this).RemoteImageBufferMessageHandlerProxy::waitForImageBufferBackendWasCreated();
>+        if (!m_backend && m_remoteRenderingBackendProxy)
>+            m_remoteRenderingBackendProxy->waitForImageBufferBackendWasCreated();
>         return m_backend.get();
>     }
> 
>     RefPtr<WebCore::ImageData> getImageData(WebCore::AlphaPremultiplication outputFormat, const WebCore::IntRect& srcRect) const override
>     {
>+        if (!m_remoteRenderingBackendProxy)
>+            return nullptr;
>+
>         auto& displayList = const_cast<RemoteImageBufferProxy*>(this)->m_drawingContext.displayList();
>-        const_cast<RemoteImageBufferProxy*>(this)->RemoteImageBufferMessageHandlerProxy::flushDisplayList(displayList);
>-        auto result = const_cast<RemoteImageBufferProxy*>(this)->RemoteImageBufferMessageHandlerProxy::getImageData(outputFormat, srcRect);
>+        if (displayList.itemCount()) {
>+            const_cast<RemoteImageBufferProxy&>(*this).flushDisplayList(displayList);
>+            displayList.clear();
>+        }
>+
>         // getImageData is synchronous, which means we've already received the CommitImageBufferFlushContext message.
>-        return result;
>+        return m_remoteRenderingBackendProxy->getImageData(outputFormat, srcRect, m_remoteResourceIdentifier);
>     }
> 
>     void putImageData(WebCore::AlphaPremultiplication inputFormat, const WebCore::ImageData& imageData, const WebCore::IntRect& srcRect, const WebCore::IntPoint& destPoint = { }, WebCore::AlphaPremultiplication destFormat = WebCore::AlphaPremultiplication::Premultiplied) override
>@@ -104,17 +120,53 @@ protected:
>     void flushDrawingContext() override
>     {
>         auto& displayList = m_drawingContext.displayList();
>-        if (displayList.itemCount())
>-            RemoteImageBufferMessageHandlerProxy::flushDisplayListAndWaitCommit(displayList);
>+        if (!displayList.itemCount() || !m_remoteRenderingBackendProxy)
>+            return;
>+
>+        TraceScope tracingScope(FlushRemoteImageBufferStart, FlushRemoteImageBufferEnd, 1);
>+        m_sentFlushIdentifier = m_remoteRenderingBackendProxy->flushDisplayListAndCommit(displayList, m_remoteResourceIdentifier);
>+
>+        // Wait for our DisplayList to be flushed but do not hang.
>+        static constexpr unsigned maxWaitingFlush = 3;
>+        for (unsigned numWaitingFlush = 0; numWaitingFlush < maxWaitingFlush && isPendingFlush(); ++numWaitingFlush)
>+            m_remoteRenderingBackendProxy->waitForFlushDisplayListWasCommitted();
>+
>+        m_remoteRenderingBackendProxy->remoteResourceCacheProxy().unlockRemoteResourcesForRemoteClient(m_remoteResourceIdentifier);
>+        displayList.clear();
>+    }
>+
>+    void flushDisplayList(const WebCore::DisplayList::DisplayList& displayList) override
>+    {
>+        if (!displayList.itemCount() || !m_remoteRenderingBackendProxy)
>+            return;
>+
>+        TraceScope tracingScope(FlushRemoteImageBufferStart, FlushRemoteImageBufferEnd);
>+        m_remoteRenderingBackendProxy->flushDisplayList(displayList, m_remoteResourceIdentifier);
>+        m_remoteRenderingBackendProxy->remoteResourceCacheProxy().unlockRemoteResourcesForRemoteClient(m_remoteResourceIdentifier);
>     }
>-    
>+
>     void willAppendItem(const WebCore::DisplayList::Item&) override
>     {
>         constexpr size_t DisplayListBatchSize = 512;
>         auto& displayList = m_drawingContext.displayList();
>-        if (displayList.itemCount() >= DisplayListBatchSize)
>-            RemoteImageBufferMessageHandlerProxy::flushDisplayList(displayList);
>+        if (displayList.itemCount() < DisplayListBatchSize || !m_remoteRenderingBackendProxy)
>+            return;
>+
>+        flushDisplayList(displayList);
>+        displayList.clear();
>+    }
>+
>+    bool lockRemoteImageBuffer(WebCore::ImageBuffer& imageBuffer) override
>+    {
>+        if (!m_remoteRenderingBackendProxy)
>+            return false;
>+        return m_remoteRenderingBackendProxy->remoteResourceCacheProxy().lockRemoteImageBufferForRemoteClient(imageBuffer, m_remoteResourceIdentifier);
>     }
>+
>+    DisplayListFlushIdentifier m_sentFlushIdentifier;
>+    DisplayListFlushIdentifier m_receivedFlushIdentifier;
>+    WebCore::RemoteResourceIdentifier m_remoteResourceIdentifier { WebCore::RemoteResourceIdentifier::generate() };
>+    WeakPtr<RemoteRenderingBackendProxy> m_remoteRenderingBackendProxy;
> };
> 
> } // namespace WebKit
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp b/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp
>index b1461b482148d2b75b40f098d940cde10ab4ffce..5d4e0820e09a514f9bfe538ea28aff2e89e82c73 100644
>--- a/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp
>+++ b/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp
>@@ -30,6 +30,7 @@
> 
> #include "GPUConnectionToWebProcess.h"
> #include "GPUProcessConnection.h"
>+#include "ImageDataReference.h"
> #include "PlatformRemoteImageBufferProxy.h"
> #include "RemoteRenderingBackendMessages.h"
> #include "RemoteRenderingBackendProxyMessages.h"
>@@ -88,38 +89,75 @@ bool RemoteRenderingBackendProxy::waitForFlushDisplayListWasCommitted()
> 
> std::unique_ptr<ImageBuffer> RemoteRenderingBackendProxy::createImageBuffer(const FloatSize& size, ShouldAccelerate shouldAccelerate, float resolutionScale, ColorSpace colorSpace)
> {
>+    RenderingMode renderingMode;
>+    std::unique_ptr<WebCore::ImageBuffer> imageBuffer;
>+
>     if (shouldAccelerate == ShouldAccelerate::Yes) {
>-        if (auto imageBuffer = AcceleratedRemoteImageBufferProxy::create(size, RenderingMode::RemoteAccelerated, resolutionScale, colorSpace, *this)) {
>-            m_imageBufferMessageHandlerMap.add(imageBuffer->remoteResourceIdentifier(), imageBuffer.get());
>-            return imageBuffer;
>-        }
>+        renderingMode = RenderingMode::RemoteAccelerated;
>+        imageBuffer = AcceleratedRemoteImageBufferProxy::create(size, resolutionScale, *this);
>+    }
>+
>+    if (!imageBuffer) {
>+        renderingMode = RenderingMode::RemoteUnaccelerated;
>+        imageBuffer = UnacceleratedRemoteImageBufferProxy::create(size, resolutionScale, *this);
>     }
> 
>-    if (auto imageBuffer = UnacceleratedRemoteImageBufferProxy::create(size, RenderingMode::RemoteUnaccelerated, resolutionScale, colorSpace, *this)) {
>-        m_imageBufferMessageHandlerMap.add(imageBuffer->remoteResourceIdentifier(), imageBuffer.get());
>+    if (imageBuffer) {
>+        send(Messages::RemoteRenderingBackend::CreateImageBuffer(size, renderingMode, resolutionScale, colorSpace, imageBuffer->remoteResourceIdentifier()), m_renderingBackendIdentifier);
>+        m_remoteResourceCacheProxy.cacheImageBuffer(imageBuffer->remoteResourceIdentifier(), imageBuffer.get());
>         return imageBuffer;
>     }
> 
>+    ASSERT_NOT_REACHED();
>     return nullptr;
> }
> 
>+RefPtr<ImageData> RemoteRenderingBackendProxy::getImageData(AlphaPremultiplication outputFormat, const IntRect& srcRect, RemoteResourceIdentifier remoteResourceIdentifier)
>+{
>+    IPC::ImageDataReference imageDataReference;
>+    sendSync(Messages::RemoteRenderingBackend::GetImageData(outputFormat, srcRect, remoteResourceIdentifier), Messages::RemoteRenderingBackend::GetImageData::Reply(imageDataReference), m_renderingBackendIdentifier, 1_s);
>+    return imageDataReference.buffer();
>+}
>+
>+void RemoteRenderingBackendProxy::flushDisplayList(const DisplayList::DisplayList& displayList, RemoteResourceIdentifier remoteResourceIdentifier)
>+{
>+    send(Messages::RemoteRenderingBackend::FlushDisplayList(displayList, remoteResourceIdentifier), m_renderingBackendIdentifier);
>+}
>+
>+DisplayListFlushIdentifier RemoteRenderingBackendProxy::flushDisplayListAndCommit(const DisplayList::DisplayList& displayList, RemoteResourceIdentifier remoteResourceIdentifier)
>+{
>+    DisplayListFlushIdentifier sentFlushIdentifier = DisplayListFlushIdentifier::generate();
>+    send(Messages::RemoteRenderingBackend::FlushDisplayListAndCommit(displayList, sentFlushIdentifier, remoteResourceIdentifier), m_renderingBackendIdentifier);
>+    return sentFlushIdentifier;
>+}
>+
> void RemoteRenderingBackendProxy::releaseRemoteResource(RemoteResourceIdentifier remoteResourceIdentifier)
> {
>-    // CreateImageBuffer message should have been received before this one.
>-    bool found = m_imageBufferMessageHandlerMap.remove(remoteResourceIdentifier);
>-    ASSERT_UNUSED(found, found);
>+    send(Messages::RemoteRenderingBackend::ReleaseRemoteResource(remoteResourceIdentifier), m_renderingBackendIdentifier);
> }
> 
> void RemoteRenderingBackendProxy::imageBufferBackendWasCreated(const FloatSize& logicalSize, const IntSize& backendSize, float resolutionScale, ColorSpace colorSpace, ImageBufferBackendHandle handle, RemoteResourceIdentifier remoteResourceIdentifier)
> {
>-    if (auto imageBuffer = m_imageBufferMessageHandlerMap.get(remoteResourceIdentifier))
>-        imageBuffer->createBackend(logicalSize, backendSize, resolutionScale, colorSpace, WTFMove(handle));
>+    auto imageBuffer = m_remoteResourceCacheProxy.cachedImageBuffer(remoteResourceIdentifier);
>+    if (!imageBuffer)
>+        return;
>+    
>+    if (imageBuffer->isAccelerated())
>+        downcast<AcceleratedRemoteImageBufferProxy>(*imageBuffer).createBackend(logicalSize, backendSize, resolutionScale, colorSpace, WTFMove(handle));
>+    else
>+        downcast<UnacceleratedRemoteImageBufferProxy>(*imageBuffer).createBackend(logicalSize, backendSize, resolutionScale, colorSpace, WTFMove(handle));
> }
> 
> void RemoteRenderingBackendProxy::flushDisplayListWasCommitted(DisplayListFlushIdentifier flushIdentifier, RemoteResourceIdentifier remoteResourceIdentifier)
> {
>-    if (auto imageBuffer = m_imageBufferMessageHandlerMap.get(remoteResourceIdentifier))
>-        imageBuffer->commitFlushContext(flushIdentifier);
>+    auto imageBuffer = m_remoteResourceCacheProxy.cachedImageBuffer(remoteResourceIdentifier);
>+    if (!imageBuffer)
>+        return;
>+
>+    if (imageBuffer->isAccelerated())
>+        downcast<AcceleratedRemoteImageBufferProxy>(*imageBuffer).commitFlushDisplayList(flushIdentifier);
>+    else
>+        downcast<UnacceleratedRemoteImageBufferProxy>(*imageBuffer).commitFlushDisplayList(flushIdentifier);
> }
> 
> } // namespace WebKit
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.h b/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.h
>index 9d290023d49721ead6cb98799d26f5a8d0ed4dbe..3fe51c5da95e37503d7dbdb45eb8697cd4263f72 100644
>--- a/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.h
>+++ b/Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.h
>@@ -31,16 +31,24 @@
> #include "ImageBufferBackendHandle.h"
> #include "MessageReceiver.h"
> #include "MessageSender.h"
>-#include "RemoteImageBufferMessageHandlerProxy.h"
>+#include "RemoteResourceCacheProxy.h"
> #include "RenderingBackendIdentifier.h"
>-#include <WebCore/ColorSpace.h>
>-#include <WebCore/DisplayList.h>
>-#include <WebCore/FloatSize.h>
> #include <WebCore/RemoteResourceIdentifier.h>
>-#include <WebCore/RenderingMode.h>
>-#include <wtf/HashMap.h>
> #include <wtf/WeakPtr.h>
> 
>+namespace WebCore {
>+namespace DisplayList {
>+class DisplayList;
>+class Item;
>+}
>+class FloatSize;
>+class ImageData;
>+enum class AlphaPremultiplication : uint8_t;
>+enum class ColorSpace : uint8_t;
>+enum class RenderingMode : uint8_t;
>+enum class ShouldAccelerate : bool;
>+}
>+
> namespace WebKit {
> 
> class RemoteRenderingBackendProxy
>@@ -52,7 +60,7 @@ public:
> 
>     ~RemoteRenderingBackendProxy();
> 
>-    RenderingBackendIdentifier renderingBackendIdentifier() const { return m_renderingBackendIdentifier; }
>+    RemoteResourceCacheProxy& remoteResourceCacheProxy() { return m_remoteResourceCacheProxy; }
> 
>     // IPC::MessageSender.
>     IPC::Connection* messageSenderConnection() const override;
>@@ -61,7 +69,11 @@ public:
>     // IPC::MessageReceiver
>     void didReceiveMessage(IPC::Connection&, IPC::Decoder&) override;
> 
>+    // Messages to be sent.
>     std::unique_ptr<WebCore::ImageBuffer> createImageBuffer(const WebCore::FloatSize&, WebCore::ShouldAccelerate, float resolutionScale, WebCore::ColorSpace);
>+    RefPtr<WebCore::ImageData> getImageData(WebCore::AlphaPremultiplication outputFormat, const WebCore::IntRect& srcRect, WebCore::RemoteResourceIdentifier);
>+    void flushDisplayList(const WebCore::DisplayList::DisplayList&, WebCore::RemoteResourceIdentifier);
>+    DisplayListFlushIdentifier flushDisplayListAndCommit(const WebCore::DisplayList::DisplayList&, WebCore::RemoteResourceIdentifier);
>     void releaseRemoteResource(WebCore::RemoteResourceIdentifier);
> 
>     bool waitForImageBufferBackendWasCreated();
>@@ -74,8 +86,7 @@ private:
>     void imageBufferBackendWasCreated(const WebCore::FloatSize& logicalSize, const WebCore::IntSize& backendSize, float resolutionScale, WebCore::ColorSpace, ImageBufferBackendHandle, WebCore::RemoteResourceIdentifier);
>     void flushDisplayListWasCommitted(DisplayListFlushIdentifier, WebCore::RemoteResourceIdentifier);
> 
>-    using ImageBufferMessageHandlerMap = HashMap<WebCore::RemoteResourceIdentifier, RemoteImageBufferMessageHandlerProxy*>;
>-    ImageBufferMessageHandlerMap m_imageBufferMessageHandlerMap;
>+    RemoteResourceCacheProxy m_remoteResourceCacheProxy { *this };
>     RenderingBackendIdentifier m_renderingBackendIdentifier { RenderingBackendIdentifier::generate() };
> };
> 
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteResourceCacheProxy.cpp b/Source/WebKit/WebProcess/GPU/graphics/RemoteResourceCacheProxy.cpp
>new file mode 100644
>index 0000000000000000000000000000000000000000..f40f419741110b9c587d05f0b258621ddf82c257
>--- /dev/null
>+++ b/Source/WebKit/WebProcess/GPU/graphics/RemoteResourceCacheProxy.cpp
>@@ -0,0 +1,129 @@
>+/*
>+ * Copyright (C) 2020 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 "RemoteResourceCacheProxy.h"
>+
>+#if ENABLE(GPU_PROCESS)
>+
>+#include "RemoteRenderingBackendProxy.h"
>+
>+namespace WebKit {
>+using namespace WebCore;
>+
>+RemoteResourceCacheProxy::RemoteResourceCacheProxy(RemoteRenderingBackendProxy& remoteRenderingBackendProxy)
>+    : m_remoteRenderingBackendProxy(remoteRenderingBackendProxy)
>+{
>+}
>+
>+void RemoteResourceCacheProxy::cacheImageBuffer(RemoteResourceIdentifier identifier, WebCore::ImageBuffer* imageBuffer)
>+{
>+    auto addResult = m_imageBuffers.add(identifier, imageBuffer);
>+    ASSERT_UNUSED(addResult, addResult.isNewEntry);
>+}
>+
>+ImageBuffer* RemoteResourceCacheProxy::cachedImageBuffer(RemoteResourceIdentifier identifier)
>+{
>+    return m_imageBuffers.get(identifier);
>+}
>+
>+void RemoteResourceCacheProxy::releaseImageBuffer(RemoteResourceIdentifier remoteResourceIdentifier)
>+{
>+    bool found = m_imageBuffers.remove(remoteResourceIdentifier);
>+    ASSERT_UNUSED(found, found);
>+
>+    // Tell the GPU process to remove this resource unless it's pending replaying back.
>+    releaseRemoteResource(remoteResourceIdentifier);
>+}
>+
>+bool RemoteResourceCacheProxy::lockRemoteImageBufferForRemoteClient(ImageBuffer& imageBuffer, RemoteResourceIdentifier remoteClientIdentifier)
>+{
>+    if (!imageBuffer.remoteResourceIdentifier())
>+        return false;
>+    
>+    if (cachedImageBuffer(imageBuffer.remoteResourceIdentifier()) != &imageBuffer) {
>+        ASSERT_NOT_REACHED();
>+        return false;
>+    }
>+
>+    lockRemoteResourceForRemoteClient(imageBuffer.remoteResourceIdentifier(), remoteClientIdentifier);
>+    return true;
>+}
>+
>+void RemoteResourceCacheProxy::lockRemoteResourceForRemoteClient(RemoteResourceIdentifier remoteResourceIdentifier, RemoteResourceIdentifier remoteClientIdentifier)
>+{
>+    // Add the "resource -> client" dependency in m_lockedRemoteResourceForRemoteClients.
>+    auto& clients = m_lockedRemoteResourceForRemoteClients.ensure(remoteResourceIdentifier, [&] {
>+        return RemoteClientsHashSet();
>+    }).iterator->value;
>+
>+    clients.add(remoteClientIdentifier);
>+}
>+
>+void RemoteResourceCacheProxy::releaseRemoteResource(RemoteResourceIdentifier remoteResourceIdentifier)
>+{
>+    ASSERT(!m_pendingUnlockRemoteResourceForRemoteClients.contains(remoteResourceIdentifier));
>+
>+    // If we have recorded resource -> client dependency before in m_lockedRemoteResourceForRemoteClients, move this
>+    // dependency to m_pendingUnlockRemoteResourceForRemoteClients. Otherwise remove the resource in the GPU Process.
>+    if (m_lockedRemoteResourceForRemoteClients.contains(remoteResourceIdentifier))
>+        m_pendingUnlockRemoteResourceForRemoteClients.add(remoteResourceIdentifier, m_lockedRemoteResourceForRemoteClients.take(remoteResourceIdentifier));
>+    else
>+        m_remoteRenderingBackendProxy.releaseRemoteResource(remoteResourceIdentifier);
>+}
>+
>+void RemoteResourceCacheProxy::unlockRemoteResourcesForRemoteClient(RemoteResourceIdentifier remoteClientIdentifier)
>+{
>+    auto removeRemoteClient = [&](RemoteResourceClientsHashMap& remoteResourceForRemoteClients, RemoteResourceIdentifier remoteClientIdentifier) {
>+        Vector<RemoteResourceIdentifier> remoteResourceClientsToBeRemoved;
>+
>+        // Remove all the resource -> client dependencies from remoteResourceClientsHashMap.
>+        for (auto& pair : remoteResourceForRemoteClients) {
>+            pair.value.remove(remoteClientIdentifier);
>+            if (pair.value.isEmpty())
>+                remoteResourceClientsToBeRemoved.append(pair.key);
>+        }
>+
>+        // Return a list of the unreferenced resources.
>+        return remoteResourceClientsToBeRemoved;
>+    };
>+
>+    // Remove all the resource -> client dependencies from m_lockedRemoteResourceForRemoteClients.
>+    for (auto remoteResourceIdentifier : removeRemoteClient(m_lockedRemoteResourceForRemoteClients, remoteClientIdentifier))
>+        m_lockedRemoteResourceForRemoteClients.remove(remoteResourceIdentifier);
>+
>+    // Remove all the resource -> client dependencies from m_pendingUnlockRemoteResourceForRemoteClients.
>+    for (auto remoteResourceIdentifier : removeRemoteClient(m_pendingUnlockRemoteResourceForRemoteClients, remoteClientIdentifier)) {
>+        // Remove the unreferenced resources from m_remoteResourceClientsPendingReleaseHashMap.
>+        m_pendingUnlockRemoteResourceForRemoteClients.remove(remoteResourceIdentifier);
>+
>+        // Tell the GPU process to remove this resource.
>+        m_remoteRenderingBackendProxy.releaseRemoteResource(remoteResourceIdentifier);
>+    }
>+}
>+
>+} // namespace WebKit
>+
>+#endif // ENABLE(GPU_PROCESS)
>diff --git a/Source/WebKit/WebProcess/GPU/graphics/RemoteResourceCacheProxy.h b/Source/WebKit/WebProcess/GPU/graphics/RemoteResourceCacheProxy.h
>new file mode 100644
>index 0000000000000000000000000000000000000000..478e4b993d775cd8d602aaf94713988d583ef4a0
>--- /dev/null
>+++ b/Source/WebKit/WebProcess/GPU/graphics/RemoteResourceCacheProxy.h
>@@ -0,0 +1,68 @@
>+/*
>+ * Copyright (C) 2020 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. ``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
>+ * 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
>+
>+#if ENABLE(GPU_PROCESS)
>+
>+#include <WebCore/RemoteResourceIdentifier.h>
>+#include <wtf/HashMap.h>
>+
>+namespace WebCore {
>+class ImageBuffer;
>+}
>+
>+namespace WebKit {
>+
>+class RemoteRenderingBackendProxy;
>+
>+class RemoteResourceCacheProxy {
>+public:
>+    RemoteResourceCacheProxy(RemoteRenderingBackendProxy&);
>+
>+    void cacheImageBuffer(WebCore::RemoteResourceIdentifier, WebCore::ImageBuffer*);
>+    WebCore::ImageBuffer* cachedImageBuffer(WebCore::RemoteResourceIdentifier);
>+    void releaseImageBuffer(WebCore::RemoteResourceIdentifier);
>+
>+    bool lockRemoteImageBufferForRemoteClient(WebCore::ImageBuffer&, WebCore::RemoteResourceIdentifier remoteClientIdentifier);
>+    void unlockRemoteResourcesForRemoteClient(WebCore::RemoteResourceIdentifier remoteClientIdentifier);
>+    
>+private:
>+    using RemoteClientsHashSet = HashSet<WebCore::RemoteResourceIdentifier>;
>+    using RemoteResourceClientsHashMap = HashMap<WebCore::RemoteResourceIdentifier, RemoteClientsHashSet>;
>+    using RemoteImageBufferProxyHashMap = HashMap<WebCore::RemoteResourceIdentifier, WebCore::ImageBuffer*>;
>+
>+    void lockRemoteResourceForRemoteClient(WebCore::RemoteResourceIdentifier, WebCore::RemoteResourceIdentifier remoteClientIdentifier);
>+    void releaseRemoteResource(WebCore::RemoteResourceIdentifier);
>+
>+    RemoteImageBufferProxyHashMap m_imageBuffers;
>+    RemoteResourceClientsHashMap m_lockedRemoteResourceForRemoteClients;
>+    RemoteResourceClientsHashMap m_pendingUnlockRemoteResourceForRemoteClients;
>+    RemoteRenderingBackendProxy& m_remoteRenderingBackendProxy;
>+};
>+
>+} // namespace WebKit
>+
>+#endif // ENABLE(GPU_PROCESS)

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Attachments on bug 217566: 411031 | 411032 | 411934 | 411947 | 412398 | 412403