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..5a396772c7894ece64b13ce10c6f3876d27139d0 100644
--- a/content/browser/renderer_host/offscreen_canvas_surface_manager.h
+++ b/content/browser/renderer_host/offscreen_canvas_surface_manager.h
@@ -20,6 +20,12 @@ class CONTENT_EXPORT OffscreenCanvasSurfaceManager
 
   static OffscreenCanvasSurfaceManager* GetInstance();
 
+  // 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 RegisterFrameSinkToItsParent(cc::FrameSinkId);
+  void UnregisterFrameSinkFromItsParent(cc::FrameSinkId);
+
   void RegisterOffscreenCanvasSurfaceInstance(cc::FrameSinkId,
                                               OffscreenCanvasSurfaceImpl*);
   void UnregisterOffscreenCanvasSurfaceInstance(cc::FrameSinkId);