[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/resources/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_LAYER_UPDATER_H_
 #define CC_RESOURCES_LAYER_UPDATER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
@@ skipping 11 matching lines @@
  public:
   // Allows updaters to store per-resource update properties.
   class CC_EXPORT Resource {
    public:
     virtual ~Resource();
 
     PrioritizedResource* texture() { return texture_.get(); }
     // TODO(reveman): partial_update should be a property of this class
     // instead of an argument passed to Update().
     virtual void Update(ResourceUpdateQueue* queue,
-                        gfx::Rect source_rect,
+                        const gfx::Rect& source_rect,
                         gfx::Vector2d dest_offset,
                         bool partial_update) = 0;
    protected:
     explicit Resource(scoped_ptr<PrioritizedResource> texture);
 
    private:
     scoped_ptr<PrioritizedResource> texture_;
 
     DISALLOW_COPY_AND_ASSIGN(Resource);
   };
 
   LayerUpdater() {}
 
   virtual scoped_ptr<Resource> CreateResource(
       PrioritizedResourceManager* manager) = 0;
   // The |resulting_opaque_rect| gives back a region of the layer that was
   // painted opaque. If the layer is marked opaque in the updater, then this
   // region should be ignored in preference for the entire layer's area.
-  virtual void PrepareToUpdate(gfx::Rect content_rect,
+  virtual void PrepareToUpdate(const gfx::Rect& content_rect,
                                gfx::Size tile_size,
                                float contents_width_scale,
                                float contents_height_scale,
                                gfx::Rect* resulting_opaque_rect) {}
   virtual void ReduceMemoryUsage() {}
 
   // Set true by the layer when it is known that the entire output is going to
   // be opaque.
   virtual void SetOpaque(bool opaque) {}
 
  protected:
   virtual ~LayerUpdater() {}
 
  private:
   friend class base::RefCounted<LayerUpdater>;
 
   DISALLOW_COPY_AND_ASSIGN(LayerUpdater);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_LAYER_UPDATER_H_