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

cc/layers/content_layer_unittest.cc

 // Copyright 2012 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/layers/content_layer.h"
 
 #include "cc/layers/content_layer_client.h"
 #include "cc/resources/bitmap_content_layer_updater.h"
 #include "cc/test/fake_rendering_stats_instrumentation.h"
 #include "cc/test/geometry_test_utils.h"
 #include "skia/ext/platform_canvas.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/rect_conversions.h"
 
 namespace cc {
 namespace {
 
 class MockContentLayerClient : public ContentLayerClient {
  public:
-  explicit MockContentLayerClient(gfx::Rect opaque_layer_rect)
+  explicit MockContentLayerClient(const gfx::Rect& opaque_layer_rect)
       : opaque_layer_rect_(opaque_layer_rect) {}
 
   virtual void PaintContents(SkCanvas* canvas,
-                             gfx::Rect clip,
+                             const gfx::Rect& clip,
                              gfx::RectF* opaque) OVERRIDE {
     *opaque = gfx::RectF(opaque_layer_rect_);
   }
   virtual void DidChangeLayerCanUseLCDText() OVERRIDE {}
 
  private:
   gfx::Rect opaque_layer_rect_;
 };
 
 TEST(ContentLayerTest, ContentLayerPainterWithDeviceScale) {
@@ skipping 16 matching lines @@
                            contents_scale,
                            contents_scale,
                            &resulting_opaque_rect);
 
   EXPECT_EQ(opaque_rect_in_content_space.ToString(),
             resulting_opaque_rect.ToString());
 }
 
 }  // namespace
 }  // namespace cc