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

content/browser/renderer_host/offscreen_canvas_surface_manager.h

Index: content/browser/renderer_host/offscreen_canvas_surface_manager.h
diff --git a/content/browser/renderer_host/offscreen_canvas_surface_manager.h b/content/browser/renderer_host/offscreen_canvas_surface_manager.h
index e53cea7037c5e09512523121927d78c2c467f543..651dc8cb3a83c6e18f9757f341f7406c1433b6aa 100644
--- a/content/browser/renderer_host/offscreen_canvas_surface_manager.h
+++ b/content/browser/renderer_host/offscreen_canvas_surface_manager.h
@@ -20,10 +20,19 @@ class CONTENT_EXPORT OffscreenCanvasSurfaceManager
 
   static OffscreenCanvasSurfaceManager* GetInstance();
 
-  void RegisterOffscreenCanvasSurfaceInstance(cc::FrameSinkId,
-                                              OffscreenCanvasSurfaceImpl*);
-  void UnregisterOffscreenCanvasSurfaceInstance(cc::FrameSinkId);
-  OffscreenCanvasSurfaceImpl* GetSurfaceInstance(cc::FrameSinkId);
+  // Registration of the frame sink with the given frame sink id to its parent
+  // frame sink (if it has one), so that parent frame is able to send signals
+  // to it on begin frame.
+  void RegisterFrameSinkToParent(const cc::FrameSinkId& frame_sink_id);
+  void UnregisterFrameSinkFromParent(const cc::FrameSinkId& frame_sink_id);
+
+  void RegisterOffscreenCanvasSurfaceInstance(
+      const cc::FrameSinkId& frame_sink_id,
+      OffscreenCanvasSurfaceImpl* offscreen_canvas_surface);
+  void UnregisterOffscreenCanvasSurfaceInstance(
+      const cc::FrameSinkId& frame_sink_id);
+  OffscreenCanvasSurfaceImpl* GetSurfaceInstance(
+      const cc::FrameSinkId& frame_sink_id);
 
  private:
   friend class OffscreenCanvasSurfaceManagerTest;