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

ui/aura/local/window_port_local.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 UI_AURA_LOCAL_WINDOW_PORT_LOCAL_H_
 #define UI_AURA_LOCAL_WINDOW_PORT_LOCAL_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "cc/surfaces/frame_sink_id.h"
@@ skipping 23 matching lines @@
   void OnVisibilityChanged(bool visible) override;
   void OnDidChangeBounds(const gfx::Rect& old_bounds,
                          const gfx::Rect& new_bounds) override;
   std::unique_ptr<ui::PropertyData> OnWillChangeProperty(
       const void* key) override;
   void OnPropertyChanged(const void* key,
                          int64_t old_value,
                          std::unique_ptr<ui::PropertyData> data) override;
   std::unique_ptr<cc::CompositorFrameSink> CreateCompositorFrameSink() override;
   cc::SurfaceId GetSurfaceId() const override;
+  void SetNeedsBeginFrames(bool needs,
+                           base::RepeatingClosure callback) override;
   void OnWindowAddedToRootWindow() override;
   void OnWillRemoveWindowFromRootWindow() override;
 
  private:
   void OnSurfaceChanged(const cc::SurfaceId& surface_id,
                         const gfx::Size& surface_size);
 
   Window* const window_;
   cc::FrameSinkId frame_sink_id_;
   cc::LocalSurfaceId local_surface_id_;
 
   base::WeakPtrFactory<WindowPortLocal> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowPortLocal);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_LOCAL_WINDOW_PORT_LOCAL_H_