Synchronize commits at end of JS task

third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h

Index: third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
diff --git a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
index 2d121a593c7edf695356e7c7a0ec0e440476c11c..9cfe51a871422cff5edec9b7d888bfa96724c915 100644
--- a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
+++ b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
@@ -91,6 +91,7 @@ class CORE_EXPORT OffscreenCanvas final
   ScriptPromise commit(RefPtr<StaticBitmapImage>,
                        bool isWebGLSoftwareRendering,
                        ScriptState*);
+  void doCommitAtEndOfTask();
 
   void detachContext() { m_context = nullptr; }
 
@@ -157,9 +158,13 @@ class CORE_EXPORT OffscreenCanvas final
   bool isPaintable() const;
 
   std::unique_ptr<OffscreenCanvasFrameDispatcher> m_frameDispatcher;
+
   Member<ScriptPromiseResolver> m_commitPromiseResolver;
+  RefPtr<StaticBitmapImage> m_currentFrame;

[Justin Novosad, 2017/03/24 17:41:53]

Could we call this m_frameToDispatchAtEndOfTask

[xlai (Olivia), 2017/03/24 18:18:52]

I don't think this name is suitable. With the latest change,
m_currentFrame can be dispatched in two different situations:
1. at the end of task, in normal situation
2. onBeginFrame, when this particular frame is an overdraw frame that user
commit
when the previous m_currentFrame has been dispatched but
the promise is not resolved yet.

+  bool m_currentFrameIsWebGLSoftwareRendering = false;
   RefPtr<StaticBitmapImage> m_overdrawFrame;
   bool m_overdrawFrameIsWebGLSoftwareRendering = false;
+
   // cc::FrameSinkId is broken into two integer components as this can be used
   // in transfer of OffscreenCanvas across threads
   // If this object is not created via