mus: Embedder can request and observe BeginFrame for embedded client.

services/ui/ws/server_window_compositor_frame_sink_manager.h

 // Copyright 2015 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 SERVICES_UI_WS_SERVER_WINDOW_COMPOSITOR_FRAME_SINK_MANAGER_H_
 #define SERVICES_UI_WS_SERVER_WINDOW_COMPOSITOR_FRAME_SINK_MANAGER_H_
 
 #include "base/macros.h"
 #include "cc/ipc/compositor_frame.mojom.h"
 #include "cc/ipc/frame_sink_manager.mojom.h"
@@ skipping 23 matching lines @@
       cc::mojom::DisplayPrivateAssociatedRequest display_request);
 
   void CreateCompositorFrameSink(
       cc::mojom::MojoCompositorFrameSinkRequest request,
       cc::mojom::MojoCompositorFrameSinkClientPtr client);
 
   // Claims this FrameSinkId will embed |surface_id| so it should own the
   // temporary reference to |surface_id|.
   void ClaimTemporaryReference(const cc::SurfaceId& surface_id);
 
+  void RequestBeginFrames(cc::mojom::FrameSinkObserverPtr observer);
+
  private:
   ServerWindow* const window_;
   cc::mojom::MojoCompositorFrameSinkPrivatePtr compositor_frame_sink_;
   cc::mojom::MojoCompositorFrameSinkPrivateRequest
       pending_compositor_frame_sink_request_;
 
   DISALLOW_COPY_AND_ASSIGN(ServerWindowCompositorFrameSinkManager);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_SERVER_WINDOW_COMPOSITOR_FRAME_SINK_MANAGER_H_