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

ui/compositor/layer.h

 // Copyright (c) 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 UI_COMPOSITOR_LAYER_H_
 #define UI_COMPOSITOR_LAYER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 298 matching lines @@
 
   // Sometimes the Layer is being updated by something other than SetCanvas
   // (e.g. the GPU process on UI_COMPOSITOR_IMAGE_TRANSPORT).
   bool layer_updated_externally() const { return layer_updated_externally_; }
 
   // Requets a copy of the layer's output as a texture or bitmap.
   void RequestCopyOfOutput(scoped_ptr<cc::CopyOutputRequest> request);
 
   // ContentLayerClient
   virtual void PaintContents(
-      SkCanvas* canvas, gfx::Rect clip, gfx::RectF* opaque) OVERRIDE;
+      SkCanvas* canvas, const gfx::Rect& clip, gfx::RectF* opaque) OVERRIDE;
   virtual void DidChangeLayerCanUseLCDText() OVERRIDE {}
 
   cc::Layer* cc_layer() { return cc_layer_; }
 
   // TextureLayerClient
   virtual unsigned PrepareTexture() OVERRIDE;
   virtual bool PrepareTextureMailbox(
       cc::TextureMailbox* mailbox,
       scoped_ptr<cc::SingleReleaseCallback>* release_callback,
       bool use_shared_memory) OVERRIDE;
@@ skipping 167 matching lines @@
   // The size of the delegated frame in DIP, set when SetShowDelegatedContent
   // was called.
   gfx::Size delegated_frame_size_in_dip_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_H_