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

cc/trees/layer_tree_host_common_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_common.h"
 
 #include <set>
 
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/base/math_util.h"
@@ skipping 178 matching lines @@
   virtual ~LayerWithForcedDrawsContent() {}
 };
 
 bool LayerWithForcedDrawsContent::DrawsContent() const { return true; }
 
 class MockContentLayerClient : public ContentLayerClient {
  public:
   MockContentLayerClient() {}
   virtual ~MockContentLayerClient() {}
   virtual void PaintContents(SkCanvas* canvas,
-                             gfx::Rect clip,
+                             const gfx::Rect& clip,
                              gfx::RectF* opaque) OVERRIDE {}
   virtual void DidChangeLayerCanUseLCDText() OVERRIDE {}
 };
 
 scoped_refptr<ContentLayer> CreateDrawableContentLayer(
     ContentLayerClient* delegate) {
   scoped_refptr<ContentLayer> to_return = ContentLayer::Create(delegate);
   to_return->SetIsDrawable(true);
   return to_return;
 }
@@ skipping 9530 matching lines @@
         fixed_layer->draw_properties().screen_space_transform.To2dTranslation(),
         container_offset);
     EXPECT_VECTOR_EQ(scroll_layer->draw_properties()
                          .screen_space_transform.To2dTranslation(),
                      container_offset - rounded_scroll_delta);
   }
 }
 
 }  // namespace
 }  // namespace cc