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

content/browser/renderer_host/offscreen_canvas_surface_impl.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_
 
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_id_allocator.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 #include "third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom.h"
 
 namespace content {
 
 class CONTENT_EXPORT OffscreenCanvasSurfaceImpl
     : public blink::mojom::OffscreenCanvasSurface {
  public:
   OffscreenCanvasSurfaceImpl(
+      const cc::FrameSinkId& parent_frame_sink_id,
       const cc::FrameSinkId& frame_sink_id,
       blink::mojom::OffscreenCanvasSurfaceClientPtr client);
   ~OffscreenCanvasSurfaceImpl() override;
 
-  static void Create(const cc::FrameSinkId& frame_sink_id,
+  static void Create(const cc::FrameSinkId& parent_frame_sink_id,
+                     const cc::FrameSinkId& frame_sink_id,
                      blink::mojom::OffscreenCanvasSurfaceClientPtr client,
                      blink::mojom::OffscreenCanvasSurfaceRequest request);
 
   void OnSurfaceCreated(const cc::SurfaceInfo& surface_info);
 
   // blink::mojom::OffscreenCanvasSurface implementation.
   void Require(const cc::SurfaceId& surface_id,
                const cc::SurfaceSequence& sequence) override;
   void Satisfy(const cc::SurfaceSequence& sequence) override;
 
   const cc::FrameSinkId& frame_sink_id() const { return frame_sink_id_; }
+
+  const cc::FrameSinkId& parent_frame_sink_id() const {
+    return parent_frame_sink_id_;
+  }
+
   const cc::LocalSurfaceId& current_local_surface_id() const {
     return current_local_surface_id_;
   }
 
  private:
   blink::mojom::OffscreenCanvasSurfaceClientPtr client_;
   mojo::StrongBindingPtr<blink::mojom::OffscreenCanvasSurface> binding_;
 
   // Surface-related state
-  cc::FrameSinkId frame_sink_id_;
+  const cc::FrameSinkId frame_sink_id_;
   cc::LocalSurfaceId current_local_surface_id_;
+  const cc::FrameSinkId parent_frame_sink_id_;
 
   DISALLOW_COPY_AND_ASSIGN(OffscreenCanvasSurfaceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_OFFSCREEN_CANVAS_SURFACE_IMPL_H_