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

cc/test/fake_scrollbar.h

Index: cc/test/fake_scrollbar.h
diff --git a/cc/test/fake_scrollbar.h b/cc/test/fake_scrollbar.h
index e1ac147fbb3b2c4f94ebc3b5df0bdff4b093f035..41152f6ec9f833c9fe5f593b8a0ec571534bc67a 100644
--- a/cc/test/fake_scrollbar.h
+++ b/cc/test/fake_scrollbar.h
@@ -28,10 +28,10 @@ class FakeScrollbar : public Scrollbar {
   virtual gfx::Rect TrackRect() const OVERRIDE;
   virtual void PaintPart(SkCanvas* canvas,
                          ScrollbarPart part,
-                         gfx::Rect content_rect) OVERRIDE;
+                         const gfx::Rect& content_rect) OVERRIDE;
 
   void set_location(gfx::Point location) { location_ = location; }
-  void set_track_rect(gfx::Rect track_rect) { track_rect_ = track_rect; }
+  void set_track_rect(const gfx::Rect& track_rect) { track_rect_ = track_rect; }
   void set_thumb_thickness(int thumb_thickness) {
       thumb_thickness_ = thumb_thickness;
   }