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

content/renderer/gpu/render_widget_compositor.h

Index: content/renderer/gpu/render_widget_compositor.h
diff --git a/content/renderer/gpu/render_widget_compositor.h b/content/renderer/gpu/render_widget_compositor.h
index 761e5a2eeacb690a8097b990c7b028bb64ff4b7c..edce7fd8b6eca5877c051e7136107a76191ed5c3 100644
--- a/content/renderer/gpu/render_widget_compositor.h
+++ b/content/renderer/gpu/render_widget_compositor.h
@@ -111,6 +111,7 @@ class CONTENT_EXPORT RenderWidgetCompositor
   void SetDeviceColorSpace(const gfx::ColorSpace& color_space);
 
   // WebLayerTreeView implementation.
+  cc::FrameSinkId getFrameSinkId() override;

[Fady Samuel, 2017/01/19 04:05:43]

Return a const cc::FrameSinkId& instead?

[xlai (Olivia), 2017/01/19 16:43:56]

Can't do that. This function is overriding another virtual function in
WebLayerTreeView, which must be creating an empty FrameSinkId in its
implementation.

   void setRootLayer(const blink::WebLayer& layer) override;
   void clearRootLayer() override;
   cc::AnimationHost* compositorAnimationHost() override;