[#5] Pass gfx structs by const ref (gfx::Vector2dF)

cc/layers/layer.cc

 // Copyright 2010 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/layer.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "base/location.h"
@@ skipping 1048 matching lines @@
 }
 
 void Layer::OnOpacityAnimated(float opacity) {
   opacity_ = opacity;
 }
 
 void Layer::OnTransformAnimated(const gfx::Transform& transform) {
   transform_ = transform;
 }
 
-void Layer::OnScrollOffsetAnimated(gfx::Vector2dF scroll_offset) {
+void Layer::OnScrollOffsetAnimated(const gfx::Vector2dF& scroll_offset) {
   // Do nothing. Scroll deltas will be sent from the compositor thread back
   // to the main thread in the same manner as during non-animated
   // compositor-driven scrolling.
 }
 
 void Layer::OnAnimationWaitingForDeletion() {
   // Animations are only deleted during PushProperties.
   SetNeedsPushProperties();
 }
 
@@ skipping 86 matching lines @@
     clip_parent_->RemoveClipChild(this);
 
   clip_parent_ = NULL;
 }
 
 void Layer::RunMicroBenchmark(MicroBenchmark* benchmark) {
   benchmark->RunOnLayer(this);
 }
 
 }  // namespace cc