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

cc/output/renderer.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_OUTPUT_RENDERER_H_
 #define CC_OUTPUT_RENDERER_H_
 
 #include "base/basictypes.h"
 #include "cc/base/cc_export.h"
 #include "cc/quads/render_pass.h"
@@ skipping 23 matching lines @@
   virtual bool HasAllocatedResourcesForTesting(RenderPass::Id id) const;
 
   // This passes ownership of the render passes to the renderer. It should
   // consume them, and empty the list. The parameters here may change from frame
   // to frame and should not be cached.
   // The |device_viewport_rect| and |device_clip_rect| are in non-y-flipped
   // window space.
   virtual void DrawFrame(RenderPassList* render_passes_in_draw_order,
                          ContextProvider* offscreen_context_provider,
                          float device_scale_factor,
-                         gfx::Rect device_viewport_rect,
-                         gfx::Rect device_clip_rect,
+                         const gfx::Rect& device_viewport_rect,
+                         const gfx::Rect& device_clip_rect,
                          bool allow_partial_swap,
                          bool disable_picture_quad_image_filtering) = 0;
 
   // Waits for rendering to finish.
   virtual void Finish() = 0;
 
   virtual void DoNoOp() {}
 
   // Puts backbuffer onscreen.
   virtual void SwapBuffers(const CompositorFrameMetadata& metadata) = 0;
   virtual void ReceiveSwapBuffersAck(const CompositorFrameAck& ack) {}
 
-  virtual void GetFramebufferPixels(void* pixels, gfx::Rect rect) = 0;
+  virtual void GetFramebufferPixels(void* pixels, const gfx::Rect& rect) = 0;
 
   virtual bool IsContextLost();
 
   virtual void SetVisible(bool visible) = 0;
 
   virtual void SendManagedMemoryStats(size_t bytes_visible,
                                       size_t bytes_visible_and_nearby,
                                       size_t bytes_allocated) = 0;
 
  protected:
   explicit Renderer(RendererClient* client, const LayerTreeSettings* settings)
       : client_(client), settings_(settings) {}
 
   RendererClient* client_;
   const LayerTreeSettings* settings_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Renderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_RENDERER_H_