Cherry-pick fa67a26. rdar://problem/110174274

    Schedule rendering via RemoteLayerTreeDrawingArea directly, rather than using a 'fake' DisplayRefreshMonitor.
    https://bugs.webkit.org/show_bug.cgi?id=257290
    <rdar://problem/109953504>

    Reviewed by Simon Fraser.

    RemoteLayerTreeDisplayRefreshMonitor is mostly just a wrapper around asking the RemoteLayerTreeDrawingArea to schedule when it wants to display next.
    This is specific to that drawing area, and can be throttled if the drawing area is failing to commit layer trees as fast as expected.

    DisplayRefreshMonitorManager caches DisplayRefreshMonitors, and shares them between all WebCore::Page/RenderingUpdateSchedulers on the same Display.
    This means if we have multiple RemoteLayerTreeDrawingAreas on the same display (and in the same process), we'll be sharing a single RemoteLayerTreeDisplayRefreshMonitor, driven at the effective rate of one of the drawing areas.

    If the first drawing area is trying to hit full frame rate, but rendering takes too long, it'll run at the fastest rate it can manage. Any other drawing areas that are using the shared display refresh
    monitor will then be throttled to that same rate, even if they could otherwise run at full speed.

    DrawingAreaCoordinatedGraphics is currently working around this by synthesizing a DisplayID for each drawing area, to prevent DisplayRefreshMonitor sharing.

    This change makes WebChromeClient pass the scheduleRenderingUpdate request onto RemoteLayerTreeDrawingArea directly, so we can avoid falling back to the RenderingUpdateScheduler/DisplayRefreshMonitor implementation.

    RemoteLayerTreeDisplayRefreshMonitor is removed, since it should never be used.

    * Source/WebCore/page/ChromeClient.h:
    (WebCore::ChromeClient::renderingUpdateFrequencyChanged):
    * Source/WebCore/page/Page.cpp:
    (WebCore::Page::windowScreenDidChange):
    (WebCore::Page::triggerRenderingUpdateForTesting):
    (WebCore::Page::timelineControllerMaximumAnimationFrameRateDidChange):
    (WebCore::Page::setIsVisuallyIdleInternal):
    (WebCore::Page::handleLowModePowerChange):
    * Source/WebCore/page/Page.h:
    * Source/WebCore/page/RenderingUpdateScheduler.cpp:
    (WebCore::RenderingUpdateScheduler::triggerRenderingUpdateForTesting): Deleted.
    * Source/WebCore/page/RenderingUpdateScheduler.h:
    * Source/WebKit/SourcesCocoa.txt:
    * Source/WebKit/WebKit.xcodeproj/project.pbxproj:
    * Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.cpp:
    (WebKit::WebChromeClient::scheduleRenderingUpdate):
    (WebKit::WebChromeClient::renderingUpdateFrequencyChanged):
    * Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.h:
    * Source/WebKit/WebProcess/WebPage/DrawingArea.h:
    (WebKit::DrawingArea::scheduleRenderingUpdate):
    (WebKit::DrawingArea::renderingUpdateFrequencyChanged):
    * Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDisplayRefreshMonitor.h: Removed.
    * Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDisplayRefreshMonitor.mm: Removed.
    * Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.h:
    * Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm:
    (WebKit::RemoteLayerTreeDrawingArea::RemoteLayerTreeDrawingArea):
    (WebKit::RemoteLayerTreeDrawingArea::createDisplayRefreshMonitor):
    (WebKit::RemoteLayerTreeDrawingArea::displayDidRefresh):
    (WebKit::RemoteLayerTreeDrawingArea::scheduleRenderingUpdate):
    (WebKit::RemoteLayerTreeDrawingArea::renderingUpdateFrequencyChanged):
    (WebKit::RemoteLayerTreeDrawingArea::willDestroyDisplayRefreshMonitor): Deleted.
    (WebKit::RemoteLayerTreeDrawingArea::adoptDisplayRefreshMonitorsFromDrawingArea): Deleted.

    Canonical link: https://commits.webkit.org/264920@main

Identifier: 263322.1543@safari-7616.1.17-branch

Source/WebCore/page/ChromeClient.h

@@ -394,6 +394,7 @@ class ChromeClient {
     virtual void triggerRenderingUpdate() = 0;
     // Schedule a rendering update that coordinates with display refresh. Returns true if scheduled. (This is only used by SVGImageChromeClient.)
     virtual bool scheduleRenderingUpdate() { return false; }
+    virtual void renderingUpdateFramesPerSecondChanged() { }
 
     virtual unsigned remoteImagesCountForTesting() const { return 0; }
 

Source/WebCore/page/Page.cpp

@@ -1411,7 +1411,9 @@ void Page::windowScreenDidChange(PlatformDisplayID displayID, std::optional<Fram
     if (m_scrollingCoordinator)
         m_scrollingCoordinator->windowScreenDidChange(displayID, m_displayNominalFramesPerSecond);
 
-    renderingUpdateScheduler().windowScreenDidChange(displayID);
+    if (auto *scheduler = existingRenderingUpdateScheduler())
+        scheduler->windowScreenDidChange(displayID);
+    chrome().client().renderingUpdateFramesPerSecondChanged();
 
     setNeedsRecalcStyleInAllFrames();
 }
@@ -1694,7 +1696,7 @@ void Page::computeUnfulfilledRenderingSteps(OptionSet<RenderingUpdateStep> reque
 void Page::triggerRenderingUpdateForTesting()
 {
     LOG_WITH_STREAM(EventLoop, stream << "Page " << this << " triggerRenderingUpdateForTesting()");
-    renderingUpdateScheduler().triggerRenderingUpdateForTesting();
+    chrome().client().triggerRenderingUpdate();
 }
 
 void Page::startTrackingRenderingUpdates()
@@ -2160,7 +2162,9 @@ void Page::resumeScriptedAnimations()
 
 void Page::timelineControllerMaximumAnimationFrameRateDidChange(DocumentTimelinesController&)
 {
-    renderingUpdateScheduler().adjustRenderingUpdateFrequency();
+    if (auto *scheduler = existingRenderingUpdateScheduler())
+        scheduler->adjustRenderingUpdateFrequency();
+    chrome().client().renderingUpdateFramesPerSecondChanged();
 }
 
 std::optional<FramesPerSecond> Page::preferredRenderingUpdateFramesPerSecond(OptionSet<PreferredRenderingUpdateOption> flags) const
@@ -2207,7 +2211,9 @@ void Page::setIsVisuallyIdleInternal(bool isVisuallyIdle)
         return;
 
     m_throttlingReasons.set(ThrottlingReason::VisuallyIdle, isVisuallyIdle);
-    renderingUpdateScheduler().adjustRenderingUpdateFrequency();
+    if (auto *scheduler = existingRenderingUpdateScheduler())
+        scheduler->adjustRenderingUpdateFrequency();
+    chrome().client().renderingUpdateFramesPerSecondChanged();
 }
 
 void Page::handleLowModePowerChange(bool isLowPowerModeEnabled)
@@ -2219,7 +2225,9 @@ void Page::handleLowModePowerChange(bool isLowPowerModeEnabled)
         return;
 
     m_throttlingReasons.set(ThrottlingReason::LowPowerMode, isLowPowerModeEnabled);
-    renderingUpdateScheduler().adjustRenderingUpdateFrequency();
+    if (auto *scheduler = existingRenderingUpdateScheduler())
+        scheduler->adjustRenderingUpdateFrequency();
+    chrome().client().renderingUpdateFramesPerSecondChanged();
 
     updateDOMTimerAlignmentInterval();
 }
@@ -3753,6 +3761,11 @@ RenderingUpdateScheduler& Page::renderingUpdateScheduler()
     return *m_renderingUpdateScheduler;
 }
 
+RenderingUpdateScheduler* Page::existingRenderingUpdateScheduler()
+{
+    return m_renderingUpdateScheduler.get();
+}
+
 void Page::forEachDocumentFromMainFrame(const LocalFrame& mainFrame, const Function<void(Document&)>& functor)
 {
     Vector<Ref<Document>> documents;

Source/WebCore/page/Page.h

@@ -510,8 +510,8 @@ class Page : public Supplementable<Page>, public CanMakeWeakPtr<Page> {
         IncludeAnimationsFrameRate  = 1 << 1
     };
     static constexpr OptionSet<PreferredRenderingUpdateOption> allPreferredRenderingUpdateOptions = { PreferredRenderingUpdateOption::IncludeThrottlingReasons, PreferredRenderingUpdateOption::IncludeAnimationsFrameRate };
-    std::optional<FramesPerSecond> preferredRenderingUpdateFramesPerSecond(OptionSet<PreferredRenderingUpdateOption> = allPreferredRenderingUpdateOptions) const;
-    Seconds preferredRenderingUpdateInterval() const;
+    WEBCORE_EXPORT std::optional<FramesPerSecond> preferredRenderingUpdateFramesPerSecond(OptionSet<PreferredRenderingUpdateOption> = allPreferredRenderingUpdateOptions) const;
+    WEBCORE_EXPORT Seconds preferredRenderingUpdateInterval() const;
 
     float topContentInset() const { return m_topContentInset; }
     WEBCORE_EXPORT void setTopContentInset(float);
@@ -1098,6 +1098,7 @@ class Page : public Supplementable<Page>, public CanMakeWeakPtr<Page> {
     void prioritizeVisibleResources();
 
     RenderingUpdateScheduler& renderingUpdateScheduler();
+    RenderingUpdateScheduler* existingRenderingUpdateScheduler();
 
     WheelEventTestMonitor& ensureWheelEventTestMonitor();
 

Source/WebCore/page/RenderingUpdateScheduler.cpp

@@ -138,11 +138,6 @@ void RenderingUpdateScheduler::displayRefreshFired()
     }
 }
 
-void RenderingUpdateScheduler::triggerRenderingUpdateForTesting()
-{
-    triggerRenderingUpdate();
-}
-
 void RenderingUpdateScheduler::triggerRenderingUpdate()
 {
     m_page.chrome().client().triggerRenderingUpdate();

Source/WebCore/page/RenderingUpdateScheduler.h

@@ -47,8 +47,6 @@ class RenderingUpdateScheduler final : public DisplayRefreshMonitorClient {
     void adjustRenderingUpdateFrequency();
     void scheduleRenderingUpdate();
 
-    void triggerRenderingUpdateForTesting();
-
     void windowScreenDidChange(PlatformDisplayID);
 
 private:

Source/WebKit/SourcesCocoa.txt

@@ -712,7 +712,6 @@ WebProcess/WebPage/RemoteLayerTree/PlatformCALayerRemoteHost.mm
 WebProcess/WebPage/RemoteLayerTree/PlatformCALayerRemoteModelHosting.mm
 WebProcess/WebPage/RemoteLayerTree/PlatformCALayerRemoteTiledBacking.cpp
 WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeContext.mm
-WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDisplayRefreshMonitor.mm
 WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm @no-unify
 WebProcess/WebPage/RemoteLayerTree/RemoteScrollbarsController.mm
 WebProcess/WebPage/RemoteLayerTree/RemoteScrollingCoordinator.mm

Source/WebKit/WebKit.xcodeproj/project.pbxproj

@@ -657,7 +657,6 @@
 		2D1E8223216FFF5100A15265 /* WKWebEvent.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D1E8221216FFF5000A15265 /* WKWebEvent.h */; };
 		2D279E1926955768004B3EEB /* PrototypeToolsSPI.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D279E1826955768004B3EEB /* PrototypeToolsSPI.h */; };
 		2D28A4971AF965A100F190C9 /* WKViewLayoutStrategy.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D28A4951AF965A100F190C9 /* WKViewLayoutStrategy.h */; };
-		2D29ECD0192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D29ECCE192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.h */; };
 		2D3A65DB1A7C3A1F00CAC637 /* WKNavigationActionRef.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D3A65D91A7C3A1F00CAC637 /* WKNavigationActionRef.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		2D3A65DF1A7C3A7D00CAC637 /* WKNavigationResponseRef.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D3A65DD1A7C3A7D00CAC637 /* WKNavigationResponseRef.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		2D3A65E31A7C3A9300CAC637 /* WKNavigationRef.h in Headers */ = {isa = PBXBuildFile; fileRef = 2D3A65E11A7C3A9300CAC637 /* WKNavigationRef.h */; settings = {ATTRIBUTES = (Private, ); }; };
@@ -3907,8 +3906,6 @@
 		2D28F3E01885CCC1004B9EAE /* WebChromeClientIOS.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = WebChromeClientIOS.mm; path = ios/WebChromeClientIOS.mm; sourceTree = "<group>"; };
 		2D28F3E21885CCC1004B9EAE /* WebEditorClientIOS.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = WebEditorClientIOS.mm; path = ios/WebEditorClientIOS.mm; sourceTree = "<group>"; };
 		2D28F3E31885CCC1004B9EAE /* WebLocalFrameLoaderClientIOS.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = WebLocalFrameLoaderClientIOS.mm; path = ios/WebLocalFrameLoaderClientIOS.mm; sourceTree = "<group>"; };
-		2D29ECCE192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RemoteLayerTreeDisplayRefreshMonitor.h; sourceTree = "<group>"; };
-		2D29ECCF192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = RemoteLayerTreeDisplayRefreshMonitor.mm; sourceTree = "<group>"; };
 		2D2ADF021636243500197E47 /* PDFPluginAnnotation.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = PDFPluginAnnotation.h; path = PDF/PDFPluginAnnotation.h; sourceTree = "<group>"; };
 		2D2ADF031636243500197E47 /* PDFPluginAnnotation.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = PDFPluginAnnotation.mm; path = PDF/PDFPluginAnnotation.mm; sourceTree = "<group>"; };
 		2D2ADF0516362DC700197E47 /* PDFPluginTextAnnotation.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = PDFPluginTextAnnotation.h; path = PDF/PDFPluginTextAnnotation.h; sourceTree = "<group>"; };
@@ -9097,8 +9094,6 @@
 				2D8949EF182044F600E898AA /* PlatformCALayerRemoteTiledBacking.h */,
 				1AB16AE8164B3A8800290D62 /* RemoteLayerTreeContext.h */,
 				1AB16AE7164B3A8800290D62 /* RemoteLayerTreeContext.mm */,
-				2D29ECCE192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.h */,
-				2D29ECCF192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.mm */,
 				1AB16ADC1648598400290D62 /* RemoteLayerTreeDrawingArea.h */,
 				1AB16ADB1648598400290D62 /* RemoteLayerTreeDrawingArea.mm */,
 				1AC009E229E0E28B00E696C4 /* RemoteScrollbarsController.h */,
@@ -14606,7 +14601,6 @@
 				2D47B56D1810714E003A3AEE /* RemoteLayerBackingStore.h in Headers */,
 				2DDF731518E95060004F5A66 /* RemoteLayerBackingStoreCollection.h in Headers */,
 				1AB16AEA164B3A8800290D62 /* RemoteLayerTreeContext.h in Headers */,
-				2D29ECD0192F2C2E00984B78 /* RemoteLayerTreeDisplayRefreshMonitor.h in Headers */,
 				1AB16ADE1648598400290D62 /* RemoteLayerTreeDrawingArea.h in Headers */,
 				1AB16AE21648656D00290D62 /* RemoteLayerTreeDrawingAreaProxy.h in Headers */,
 				0FF24A2E1879E4BC003ABF0C /* RemoteLayerTreeDrawingAreaProxyMessages.h in Headers */,

Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.cpp

@@ -1063,6 +1063,19 @@ void WebChromeClient::triggerRenderingUpdate()
         m_page.drawingArea()->triggerRenderingUpdate();
 }
 
+bool WebChromeClient::scheduleRenderingUpdate()
+{
+    if (m_page.drawingArea())
+        return m_page.drawingArea()->scheduleRenderingUpdate();
+    return false;
+}
+
+void WebChromeClient::renderingUpdateFramesPerSecondChanged()
+{
+    if (m_page.drawingArea())
+        m_page.drawingArea()->renderingUpdateFramesPerSecondChanged();
+}
+
 unsigned WebChromeClient::remoteImagesCountForTesting() const
 {
     return m_page.remoteImagesCountForTesting();

Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.h

@@ -231,6 +231,8 @@ class WebChromeClient final : public WebCore::ChromeClient {
     void setNeedsOneShotDrawingSynchronization() final;
     bool shouldTriggerRenderingUpdate(unsigned rescheduledRenderingUpdateCount) const final;
     void triggerRenderingUpdate() final;
+    bool scheduleRenderingUpdate() final;
+    void renderingUpdateFramesPerSecondChanged() final;
     unsigned remoteImagesCountForTesting() const final; 
 
     void contentRuleListNotification(const URL&, const WebCore::ContentRuleListResults&) final;

Source/WebKit/WebProcess/WebPage/DrawingArea.h

@@ -126,6 +126,8 @@ class DrawingArea : public IPC::MessageReceiver, public WebCore::DisplayRefreshM
     virtual void addRootFrame(WebCore::FrameIdentifier) { }
     // FIXME: Add a corresponding removeRootFrame.
     virtual void triggerRenderingUpdate() = 0;
+    virtual bool scheduleRenderingUpdate() { return false; }
+    virtual void renderingUpdateFramesPerSecondChanged() { }
 
     virtual void willStartRenderingUpdateDisplay();
     virtual void didCompleteRenderingUpdateDisplay();