[#6]Pass gfx structs by const ref (gfx::Vector2d)

cc/resources/bitmap_skpicture_content_layer_updater.h

 // Copyright 2011 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_BITMAP_SKPICTURE_CONTENT_LAYER_UPDATER_H_
 #define CC_RESOURCES_BITMAP_SKPICTURE_CONTENT_LAYER_UPDATER_H_
 
 #include "cc/resources/skpicture_content_layer_updater.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace cc {
 
 // This class records the content_rect into an SkPicture, then software
 // rasterizes the SkPicture into bitmaps for each tile. This implements
 // LayerTreeSettingSettings::per_tile_painting_enabled.
 class BitmapSkPictureContentLayerUpdater : public SkPictureContentLayerUpdater {
  public:
   class Resource : public ContentLayerUpdater::Resource {
    public:
     Resource(BitmapSkPictureContentLayerUpdater* updater,
              scoped_ptr<PrioritizedResource> texture);
 
     virtual void Update(ResourceUpdateQueue* queue,
                         const gfx::Rect& source_rect,
-                        gfx::Vector2d dest_offset,
+                        const gfx::Vector2d& dest_offset,
                         bool partial_update) OVERRIDE;
 
    private:
     SkBitmap bitmap_;
     BitmapSkPictureContentLayerUpdater* updater_;
 
     DISALLOW_COPY_AND_ASSIGN(Resource);
   };
 
   static scoped_refptr<BitmapSkPictureContentLayerUpdater> Create(
@@ skipping 12 matching lines @@
       RenderingStatsInstrumentation* stats_instrumentation,
       int layer_id);
   virtual ~BitmapSkPictureContentLayerUpdater();
 
   DISALLOW_COPY_AND_ASSIGN(BitmapSkPictureContentLayerUpdater);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_BITMAP_SKPICTURE_CONTENT_LAYER_UPDATER_H_