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

cc/trees/quad_culler_unittest.cc

Index: cc/trees/quad_culler_unittest.cc
diff --git a/cc/trees/quad_culler_unittest.cc b/cc/trees/quad_culler_unittest.cc
index c07a0a79e044ed02e9e40e8f15d2c88b5c615dbb..880035a04cd531e8b07550acbdd096e58b2bba67 100644
--- a/cc/trees/quad_culler_unittest.cc
+++ b/cc/trees/quad_culler_unittest.cc
@@ -30,7 +30,7 @@ namespace {
 class TestOcclusionTrackerImpl
     : public TestOcclusionTrackerBase<LayerImpl, RenderSurfaceImpl> {
  public:
-  TestOcclusionTrackerImpl(gfx::Rect scissor_rect_in_screen,
+  TestOcclusionTrackerImpl(const gfx::Rect& scissor_rect_in_screen,
                            bool record_metrics_for_frame = true)
       : TestOcclusionTrackerBase(scissor_rect_in_screen,
                                  record_metrics_for_frame) {}
@@ -52,10 +52,10 @@ class QuadCullerTest : public testing::Test {
 
   scoped_ptr<TiledLayerImpl> MakeLayer(TiledLayerImpl* parent,
                                        const gfx::Transform& draw_transform,
-                                       gfx::Rect layer_rect,
+                                       const gfx::Rect& layer_rect,
                                        float opacity,
                                        bool opaque,
-                                       gfx::Rect layer_opaque_rect,
+                                       const gfx::Rect& layer_opaque_rect,
                                        LayerImplList& surface_layer_list) {
     scoped_ptr<TiledLayerImpl> layer =
         TiledLayerImpl::Create(host_impl_.active_tree(), layer_id_++);