Ensure SurfaceManager is only ever used from one thread.

cc/surfaces/surface_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 CC_SURFACES_SURFACE_MANAGER_H_
 #define CC_SURFACES_SURFACE_MANAGER_H_
 
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
+#include "base/threading/thread_checker.h"
 #include "cc/surfaces/surface_damage_observer.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace cc {
 class CompositorFrame;
 class Surface;
 
 class CC_SURFACES_EXPORT SurfaceManager {
  public:
@@ skipping 12 matching lines @@
   void RemoveObserver(SurfaceDamageObserver* obs) {
     observer_list_.RemoveObserver(obs);
   }
 
   void SurfaceModified(SurfaceId surface_id);
 
  private:
   typedef base::hash_map<SurfaceId, Surface*> SurfaceMap;
   SurfaceMap surface_map_;
   ObserverList<SurfaceDamageObserver> observer_list_;
+  base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_MANAGER_H_