[#6]Pass gfx structs by const ref (gfx::Vector2d)

cc/trees/layer_tree_host_unittest_scroll.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/trees/layer_tree_host.h"
 
 #include "base/memory/weak_ptr.h"
 #include "cc/layers/content_layer.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
@@ skipping 54 matching lines @@
         PostSetNeedsCommitToMainThread();
         break;
       case 1:
         EXPECT_VECTOR_EQ(root->scroll_offset(), second_scroll_);
         EXPECT_VECTOR_EQ(root->ScrollDelta(), scroll_amount_);
         EndTest();
         break;
     }
   }
 
-  virtual void ApplyScrollAndScale(gfx::Vector2d scroll_delta,
+  virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float scale) OVERRIDE {
     num_scrolls_++;
   }
 
   virtual void AfterTest() OVERRIDE { EXPECT_EQ(1, num_scrolls_); }
 
  private:
   gfx::Vector2d initial_scroll_;
   gfx::Vector2d second_scroll_;
   gfx::Vector2d scroll_amount_;
@@ skipping 216 matching lines @@
                impl->SourceAnimationFrameNumber() == 4) {
       // Final draw after the second aborted commit.
       EXPECT_VECTOR_EQ(root_scroll_layer->ScrollDelta(), gfx::Vector2d());
       EXPECT_VECTOR_EQ(root_scroll_layer->scroll_offset(),
                        initial_scroll_ + impl_scroll_ + impl_scroll_ +
                            impl_scroll_ + second_main_scroll_);
       EndTest();
     }
   }
 
-  virtual void ApplyScrollAndScale(gfx::Vector2d scroll_delta,
+  virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float scale) OVERRIDE {
     num_impl_scrolls_++;
   }
 
   virtual void AfterTest() OVERRIDE {
     EXPECT_EQ(3, num_impl_scrolls_);
     // Verify that the embedder sees aborted commits as real commits.
     EXPECT_EQ(4, num_will_begin_main_frames_);
     EXPECT_EQ(4, num_did_begin_main_frames_);
     EXPECT_EQ(4, num_will_commits_);
@@ skipping 135 matching lines @@
     // will stall the test).
     if (layer_tree_host()->source_frame_number() < 2) {
       layer_tree_host()->SetNeedsCommit();
     }
   }
 
   void DidScroll() {
     final_scroll_offset_ = expected_scroll_layer_->scroll_offset();
   }
 
-  virtual void ApplyScrollAndScale(gfx::Vector2d scroll_delta,
+  virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float scale) OVERRIDE {
     num_scrolls_++;
   }
 
   virtual void Layout() OVERRIDE {
     EXPECT_VECTOR_EQ(gfx::Vector2d(),
                      expected_no_scroll_layer_->scroll_offset());
 
     switch (layer_tree_host()->source_frame_number()) {
       case 0:
@@ skipping 319 matching lines @@
         EXPECT_VECTOR_EQ(
             root->scroll_offset(),
             initial_scroll_ + main_thread_scroll_ + impl_thread_scroll1_);
         EXPECT_VECTOR_EQ(root->ScrollDelta(), impl_thread_scroll2_);
         EXPECT_VECTOR_EQ(root->sent_scroll_delta(), gfx::Vector2d());
         EndTest();
         break;
     }
   }
 
-  virtual void ApplyScrollAndScale(gfx::Vector2d scroll_delta,
+  virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float scale) OVERRIDE {
     num_scrolls_++;
   }
 
   virtual void AfterTest() OVERRIDE { EXPECT_EQ(1, num_scrolls_); }
 
  private:
   gfx::Vector2d initial_scroll_;
   gfx::Vector2d main_thread_scroll_;
   gfx::Vector2d impl_thread_scroll1_;
@@ skipping 297 matching lines @@
     RunTest(true, false, false);
 }
 
 TEST_F(LayerTreeHostScrollTestLayerStructureChange, ScrollDestroyWholeTree) {
     scroll_destroy_whole_tree_ = true;
     RunTest(true, false, false);
 }
 
 }  // namespace
 }  // namespace cc