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

cc/animation/layer_animation_controller.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/animation/layer_animation_controller.h"
 
 #include <algorithm>
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_delegate.h"
@@ skipping 750 matching lines @@
 }
 
 void LayerAnimationController::NotifyObserversFilterAnimated(
     const FilterOperations& filters) {
   FOR_EACH_OBSERVER(LayerAnimationValueObserver,
                     value_observers_,
                     OnFilterAnimated(filters));
 }
 
 void LayerAnimationController::NotifyObserversScrollOffsetAnimated(
-    gfx::Vector2dF scroll_offset) {
+    const gfx::Vector2dF& scroll_offset) {
   FOR_EACH_OBSERVER(LayerAnimationValueObserver,
                     value_observers_,
                     OnScrollOffsetAnimated(scroll_offset));
 }
 
 void LayerAnimationController::NotifyObserversAnimationWaitingForDeletion() {
   FOR_EACH_OBSERVER(LayerAnimationValueObserver,
                     value_observers_,
                     OnAnimationWaitingForDeletion());
 }
@@ skipping 13 matching lines @@
         value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != NULL)
       if (obs->IsActive())
         return true;
   }
   return false;
 }
 
 }  // namespace cc