ElementAnimations should hold an ObservableList of AnimationPlayers.

cc/animation/element_animations.h

 // Copyright 2015 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_ANIMATION_ELEMENT_ANIMATIONS_H_
 #define CC_ANIMATION_ELEMENT_ANIMATIONS_H_
 
 #include <bitset>
 #include <memory>
 #include <vector>
 
-#include "base/containers/linked_list.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
 #include "base/time/time.h"
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/animation_events.h"
 #include "cc/animation/target_property.h"
 #include "cc/base/cc_export.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/transform.h"
 
 namespace gfx {
@@ skipping 30 matching lines @@
   void InitAffectedElementTypes();
   void ClearAffectedElementTypes();
 
   void ElementRegistered(ElementId element_id, ElementListType list_type);
   void ElementUnregistered(ElementId element_id, ElementListType list_type);
 
   void AddPlayer(AnimationPlayer* player);
   void RemovePlayer(AnimationPlayer* player);
   bool IsEmpty() const;
 
-  typedef base::LinkedList<AnimationPlayer> PlayersList;
-  typedef base::LinkNode<AnimationPlayer> PlayersListNode;
-  const PlayersList& players_list() const { return *players_list_.get(); }
+  typedef base::ObserverList<AnimationPlayer> PlayersList;
+  PlayersList& players_list() const { return *players_list_.get(); }
 
   // Ensures that the list of active animations on the main thread and the impl
   // thread are kept in sync. This function does not take ownership of the impl
   // thread ElementAnimations.
   void PushPropertiesTo(
       scoped_refptr<ElementAnimations> element_animations_impl);
 
   void AddAnimation(std::unique_ptr<Animation> animation);
   void PauseAnimation(int animation_id, base::TimeDelta time_offset);
   void RemoveAnimation(int animation_id);
@@ skipping 219 matching lines @@
   struct PropertyAnimationState filter_animation_state_;
   struct PropertyAnimationState opacity_animation_state_;
   struct PropertyAnimationState transform_animation_state_;
 
   DISALLOW_COPY_AND_ASSIGN(ElementAnimations);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ELEMENT_ANIMATIONS_H_