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

cc/trees/layer_tree_host_perftest.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 <sstream>
 
 #include "base/file_util.h"
 #include "base/files/file_path.h"
@@ skipping 320 matching lines @@
 class PageScaleImplSidePaintingPerfTest
     : public LayerTreeHostPerfTestJsonReader {
  public:
   PageScaleImplSidePaintingPerfTest()
       : max_scale_(16.f), min_scale_(1.f / max_scale_) {}
 
   virtual void SetupTree() OVERRIDE {
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, min_scale_, max_scale_);
   }
 
-  virtual void ApplyScrollAndScale(gfx::Vector2d scroll_delta,
+  virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float scale_delta) OVERRIDE {
     float page_scale_factor = layer_tree_host()->page_scale_factor();
     page_scale_factor *= scale_delta;
     layer_tree_host()->SetPageScaleFactorAndLimits(
         page_scale_factor, min_scale_, max_scale_);
   }
 
   virtual void AnimateLayers(LayerTreeHostImpl* host_impl,
                              base::TimeTicks monotonic_time) OVERRIDE {
     if (!host_impl->pinch_gesture_active()) {
@@ skipping 36 matching lines @@
 
 TEST_F(PageScaleImplSidePaintingPerfTest, HeavyPage) {
   measure_commit_cost_ = true;
   SetTestName("heavy_page_page_scale");
   ReadTestFile("heavy_layer_tree");
   RunTestWithImplSidePainting();
 }
 
 }  // namespace
 }  // namespace cc