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

cc/layers/picture_layer_impl_unittest.cc

Index: cc/layers/picture_layer_impl_unittest.cc
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 8c6412d672ccfbda2763b70ad9ca618b7e1291f4..c3b569d1643be96ae08d6a88637549749fe6b59b 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -57,7 +57,7 @@ class PictureLayerImplTest : public testing::Test {
     host_impl_.InitializeRenderer(CreateFakeOutputSurface());
   }
 
-  void SetupDefaultTrees(gfx::Size layer_bounds) {
+  void SetupDefaultTrees(const gfx::Size& layer_bounds) {
     gfx::Size tile_size(100, 100);
 
     scoped_refptr<FakePicturePileImpl> pending_pile =
@@ -76,8 +76,8 @@ class PictureLayerImplTest : public testing::Test {
         host_impl_.active_tree()->LayerById(id_));
   }
 
-  void SetupDefaultTreesWithFixedTileSize(gfx::Size layer_bounds,
-                                          gfx::Size tile_size) {
+  void SetupDefaultTreesWithFixedTileSize(const gfx::Size& layer_bounds,
+                                          const gfx::Size& tile_size) {
     SetupDefaultTrees(layer_bounds);
     pending_layer_->set_fixed_tile_size(tile_size);
     active_layer_->set_fixed_tile_size(tile_size);