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

cc/test/layer_test_common.h

 // 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.
 
 #ifndef CC_TEST_LAYER_TEST_COMMON_H_
 #define CC_TEST_LAYER_TEST_COMMON_H_
 
 #define EXPECT_SET_NEEDS_COMMIT(expect, code_to_test)                 \
   do {                                                                \
     EXPECT_CALL(*layer_tree_host_, SetNeedsCommit()).Times((expect)); \
@@ skipping 11 matching lines @@
 namespace gfx { class Rect; }
 
 namespace cc {
 class QuadList;
 
 class LayerTestCommon {
  public:
   static const char* quad_string;
 
   static void VerifyQuadsExactlyCoverRect(const QuadList& quads,
-                                          gfx::Rect rect);
+                                          const gfx::Rect& rect);
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_LAYER_TEST_COMMON_H_