Ensure that PresentThreadPool is initialized on the UI thread.

ui/gfx/surface/accelerated_surface_win.h

 // Copyright (c) 2012 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_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_
 #define UI_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_
 #pragma once
 
 #include <d3d9.h>
 
@@ skipping 73 matching lines @@
 
   // Synchronously present a frame with no acknowledgement.
   bool Present(gfx::NativeWindow window);
 
   // Temporarily release resources until a new surface is asynchronously
   // presented. Present will not be able to represent the last surface after
   // calling this and will return false.
   void Suspend();
 
  private:
-  scoped_refptr<AcceleratedPresenter> presenter_;
+  // Immutable and accessible on any thread.
+  const scoped_refptr<AcceleratedPresenter> presenter_;
   DISALLOW_COPY_AND_ASSIGN(AcceleratedSurface);
 };
 
 #endif  // UI_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_