zero-copy: Clarify to allocate/destroy GpuMemoryBuffer on any thread and use it on the main thread o

ui/ozone/platform/caca/caca_window_manager.h

 // Copyright 2014 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_OZONE_PLATFORM_CACA_CACA_WINDOW_MANAGER_H_
 #define UI_OZONE_PLATFORM_CACA_CACA_WINDOW_MANAGER_H_
 
 #include "base/id_map.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "ui/ozone/public/surface_factory_ozone.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace ui {
 
 class CacaWindow;
 
@@ skipping 10 matching lines @@
 
   // ui::SurfaceFactoryOzone overrides:
   bool LoadEGLGLES2Bindings(
       AddGLLibraryCallback add_gl_library,
       SetGLGetProcAddressProcCallback set_gl_get_proc_address) override;
   scoped_ptr<SurfaceOzoneCanvas> CreateCanvasForWidget(
       gfx::AcceleratedWidget widget) override;
 
  private:
   IDMap<CacaWindow> windows_;
+  base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(CacaWindowManager);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_CACA_CACA_WINDOW_MANAGER_H_