Replace more ObserverList with base::ObserverList.

ui/compositor/layer_animator.h

 // Copyright (c) 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.
 
 #ifndef UI_COMPOSITOR_LAYER_ANIMATOR_H_
 #define UI_COMPOSITOR_LAYER_ANIMATOR_H_
 
 #include <deque>
 #include <vector>
 
@@ skipping 331 matching lines @@
   // This prevents the animator from automatically stepping through animations
   // and allows for manual stepping.
   bool disable_timer_for_test_;
 
   // Prevents timer adjustments in case when we start multiple animations
   // with preemption strategies that discard previous animations.
   bool adding_animations_;
 
   // Observers are notified when layer animations end, are scheduled or are
   // aborted.
-  ObserverList<LayerAnimationObserver> observers_;
+  base::ObserverList<LayerAnimationObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerAnimator);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_ANIMATOR_H_