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

cc/quads/checkerboard_draw_quad.cc

Index: cc/quads/checkerboard_draw_quad.cc
diff --git a/cc/quads/checkerboard_draw_quad.cc b/cc/quads/checkerboard_draw_quad.cc
index 5e17d885f48456eef83e57d9309d5198a2dfe8d3..57f776da46795f4c67c3121375d6aa34603064dd 100644
--- a/cc/quads/checkerboard_draw_quad.cc
+++ b/cc/quads/checkerboard_draw_quad.cc
@@ -16,7 +16,7 @@ scoped_ptr<CheckerboardDrawQuad> CheckerboardDrawQuad::Create() {
 }
 
 void CheckerboardDrawQuad::SetNew(const SharedQuadState* shared_quad_state,
-                                  gfx::Rect rect,
+                                  const gfx::Rect& rect,
                                   SkColor color) {
   gfx::Rect opaque_rect = SkColorGetA(color) == 255 ? rect : gfx::Rect();
   gfx::Rect visible_rect = rect;
@@ -27,9 +27,9 @@ void CheckerboardDrawQuad::SetNew(const SharedQuadState* shared_quad_state,
 }
 
 void CheckerboardDrawQuad::SetAll(const SharedQuadState* shared_quad_state,
-                                  gfx::Rect rect,
-                                  gfx::Rect opaque_rect,
-                                  gfx::Rect visible_rect,
+                                  const gfx::Rect& rect,
+                                  const gfx::Rect& opaque_rect,
+                                  const gfx::Rect& visible_rect,
                                   bool needs_blending,
                                   SkColor color) {
   DrawQuad::SetAll(shared_quad_state, DrawQuad::CHECKERBOARD, rect, opaque_rect,