Make OffscreenCanvas animation in sync with its placeholder canvas's parent frame rate

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

Index: third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
diff --git a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
index 4a4755592a1d9bf6503af65551366df75341d915..43650f22b641efa62b0bad22210bec44af813432 100644
--- a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
+++ b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
@@ -236,6 +236,7 @@ OffscreenCanvasFrameDispatcher* OffscreenCanvas::getOrCreateFrameDispatcher() {
 ScriptPromise OffscreenCanvas::commit(RefPtr<StaticBitmapImage> image,
                                       bool isWebGLSoftwareRendering,
                                       ScriptState* scriptState) {
+  getOrCreateFrameDispatcher()->setNeedsBeginFrame(true);
   if (m_commitPromiseResolver) {
     if (image) {
       m_overdrawFrame = std::move(image);
@@ -266,6 +267,7 @@ void OffscreenCanvas::beginFrame() {
   } else if (m_commitPromiseResolver) {
     m_commitPromiseResolver->resolve();
     m_commitPromiseResolver.clear();
+    getOrCreateFrameDispatcher()->setNeedsBeginFrame(false);

[Justin Novosad, 2017/01/19 18:06:49]

Kudos for putting this in the right place.  A comment would help to explain why
we don't need this in the case where we have an overdrawFrame.

[xlai (Olivia), 2017/01/19 19:14:34]

Done.

   }
 }