Adds BeginFrameControl via DevTools.

ui/aura/mus/mus_context_factory.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 UI_AURA_MUS_MUS_CONTEXT_FACTORY_H_
 #define UI_AURA_MUS_MUS_CONTEXT_FACTORY_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 32 matching lines @@
   void SetDisplayVisible(ui::Compositor* compositor, bool visible) override;
   void ResizeDisplay(ui::Compositor* compositor,
                      const gfx::Size& size) override;
   void SetDisplayColorSpace(ui::Compositor* compositor,
                             const gfx::ColorSpace& color_space) override {}
   void SetAuthoritativeVSyncInterval(ui::Compositor* compositor,
                                      base::TimeDelta interval) override {}
   void SetDisplayVSyncParameters(ui::Compositor* compositor,
                                  base::TimeTicks timebase,
                                  base::TimeDelta interval) override {}
+  void SwapBeginFrameSource(
+      ui::Compositor* compositor,
+      std::unique_ptr<cc::BeginFrameSource>* begin_frame_source) override {}
   void SetOutputIsSecure(ui::Compositor* compositor, bool secure) override {}
   void AddObserver(ui::ContextFactoryObserver* observer) override {}
   void RemoveObserver(ui::ContextFactoryObserver* observer) override {}
 
   cc::SurfaceManager surface_manager_;
   uint32_t next_sink_id_;
   ui::RasterThreadHelper raster_thread_helper_;
   GpuService* gpu_service_;
 
   DISALLOW_COPY_AND_ASSIGN(MusContextFactory);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_MUS_CONTEXT_FACTORY_H_