[#7] Pass gfx structs by const ref (gfx::Size)

cc/test/tiled_layer_test_common.cc

Index: cc/test/tiled_layer_test_common.cc
diff --git a/cc/test/tiled_layer_test_common.cc b/cc/test/tiled_layer_test_common.cc
index 6dddfd33888dedf1baf6fe461529449bddd9487c..e39765e58f01f5d15abe7ea9a2cf292fa7f5f47e 100644
--- a/cc/test/tiled_layer_test_common.cc
+++ b/cc/test/tiled_layer_test_common.cc
@@ -35,7 +35,7 @@ FakeLayerUpdater::FakeLayerUpdater() : prepare_count_(0), update_count_(0) {}
 FakeLayerUpdater::~FakeLayerUpdater() {}
 
 void FakeLayerUpdater::PrepareToUpdate(const gfx::Rect& content_rect,
-                                       gfx::Size tile_size,
+                                       const gfx::Size& tile_size,
                                        float contents_width_scale,
                                        float contents_height_scale,
                                        gfx::Rect* resulting_opaque_rect) {
@@ -148,7 +148,7 @@ LayerUpdater* FakeTiledLayer::Updater() const {
 }
 
 void FakeTiledLayerWithScaledBounds::SetContentBounds(
-    gfx::Size content_bounds) {
+    const gfx::Size& content_bounds) {
   forced_content_bounds_ = content_bounds;
   draw_properties().content_bounds = forced_content_bounds_;
 }