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

cc/test/skia_common.h

 // Copyright 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 CC_TEST_SKIA_COMMON_H_
 #define CC_TEST_SKIA_COMMON_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkFlattenable.h"
 #include "third_party/skia/include/core/SkPixelRef.h"
 
 namespace gfx {
 class Rect;
 class Size;
 }
 
 namespace cc {
 class Picture;
 
 void DrawPicture(unsigned char* buffer,
                  const gfx::Rect& layer_rect,
                  scoped_refptr<Picture> picture);
 
-void CreateBitmap(const gfx::Size& size, const char* uri, SkBitmap* bitmap);
+void CreateBitmap(gfx::Size size, const char* uri, SkBitmap* bitmap);
 
 }  // namespace cc
 
 #endif  // CC_TEST_SKIA_COMMON_H_