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

content/browser/aura/software_output_device_ozone.h

 // Copyright 2013 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 CONTENT_BROWSER_AURA_SOFTWARE_OUTPUT_DEVICE_OZONE_H_
 #define CONTENT_BROWSER_AURA_SOFTWARE_OUTPUT_DEVICE_OZONE_H_
 
 #include "cc/output/software_output_device.h"
 #include "content/common/content_export.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace ui {
 class Compositor;
 }
 
 namespace content {
 
 // Ozone implementation which relies on software rendering. Ozone will present
 // an accelerated widget as a SkCanvas. SoftwareOutputDevice will then use the
 // Ozone provided canvas to draw.
 class CONTENT_EXPORT SoftwareOutputDeviceOzone
     : public cc::SoftwareOutputDevice {
  public:
   explicit SoftwareOutputDeviceOzone(ui::Compositor* compositor);
   virtual ~SoftwareOutputDeviceOzone();
 
   virtual void Resize(gfx::Size viewport_size) OVERRIDE;
-  virtual SkCanvas* BeginPaint(gfx::Rect damage_rect) OVERRIDE;
+  virtual SkCanvas* BeginPaint(const gfx::Rect& damage_rect) OVERRIDE;
   virtual void EndPaint(cc::SoftwareFrameData* frame_data) OVERRIDE;
 
  private:
   ui::Compositor* compositor_;
 
   gfx::AcceleratedWidget realized_widget_;
 
   DISALLOW_COPY_AND_ASSIGN(SoftwareOutputDeviceOzone);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_AURA_SOFTWARE_OUTPUT_DEVICE_OZONE_H_