[#7] Pass gfx structs by const ref (gfx::Size)

cc/resources/shared_bitmap_manager.h

 // Copyright 2013 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_RESOURCES_SHARED_BITMAP_MANAGER_H_
 #define CC_RESOURCES_SHARED_BITMAP_MANAGER_H_
 
 #include "base/basictypes.h"
 #include "cc/base/cc_export.h"
 #include "cc/resources/shared_bitmap.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
 class CC_EXPORT SharedBitmapManager {
  public:
   SharedBitmapManager() {}
 
-  virtual scoped_ptr<SharedBitmap> AllocateSharedBitmap(gfx::Size) = 0;
+  virtual scoped_ptr<SharedBitmap> AllocateSharedBitmap(const gfx::Size&) = 0;
   virtual scoped_ptr<SharedBitmap> GetSharedBitmapFromId(
-      gfx::Size,
+      const gfx::Size&,
       const SharedBitmapId&) = 0;
   virtual scoped_ptr<SharedBitmap> GetBitmapForSharedMemory(
       base::SharedMemory*) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SharedBitmapManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_SHARED_BITMAP_MANAGER_H_