CC Animation: Make LayerAnimationController to have just one value observer.

cc/animation/layer_animation_controller.h

 // 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.
 
 #ifndef CC_ANIMATION_LAYER_ANIMATION_CONTROLLER_H_
 #define CC_ANIMATION_LAYER_ANIMATION_CONTROLLER_H_
 
 #include <bitset>
 #include <memory>
 #include <vector>
@@ skipping 83 matching lines @@
 
   void SetAnimationHost(AnimationHost* host);
   AnimationHost* animation_host() { return host_; }
 
   void NotifyAnimationStarted(const AnimationEvent& event);
   void NotifyAnimationFinished(const AnimationEvent& event);
   void NotifyAnimationAborted(const AnimationEvent& event);
   void NotifyAnimationPropertyUpdate(const AnimationEvent& event);
   void NotifyAnimationTakeover(const AnimationEvent& event);
 
-  void AddValueObserver(LayerAnimationValueObserver* observer);
-  void RemoveValueObserver(LayerAnimationValueObserver* observer);
+  void set_value_observer(LayerAnimationValueObserver* observer) {
+    value_observer_ = observer;
+  }
+
+  bool needs_active_value_observations() const {
+    return needs_active_value_observations_;
+  }
+  bool needs_pending_value_observations() const {
+    return needs_pending_value_observations_;
+  }
+
+  void set_needs_active_value_observations(
+      bool needs_active_value_observations) {
+    needs_active_value_observations_ = needs_active_value_observations;
+  }
+  void set_needs_pending_value_observations(
+      bool needs_pending_value_observations) {
+    needs_pending_value_observations_ = needs_pending_value_observations;
+  }
 
   void AddEventObserver(LayerAnimationEventObserver* observer);
   void RemoveEventObserver(LayerAnimationEventObserver* observer);
 
   void set_value_provider(LayerAnimationValueProvider* provider) {
     value_provider_ = provider;
   }
 
   void remove_value_provider(LayerAnimationValueProvider* provider) {
     if (value_provider_ == provider)
@@ skipping 112 matching lines @@
 
   AnimationHost* host_;
   int id_;
   std::vector<std::unique_ptr<Animation>> animations_;
 
   // This is used to ensure that we don't spam the animation host.
   bool is_active_;
 
   base::TimeTicks last_tick_time_;
 
-  base::ObserverList<LayerAnimationValueObserver> value_observers_;
   base::ObserverList<LayerAnimationEventObserver> event_observers_;
+  LayerAnimationValueObserver* value_observer_;
+  LayerAnimationValueProvider* value_provider_;
+  AnimationDelegate* layer_animation_delegate_;
 
-  LayerAnimationValueProvider* value_provider_;
-
-  AnimationDelegate* layer_animation_delegate_;
+  bool needs_active_value_observations_;
+  bool needs_pending_value_observations_;
 
   // Only try to start animations when new animations are added or when the
   // previous attempt at starting animations failed to start all animations.
   bool needs_to_start_animations_;
 
   bool scroll_offset_animation_was_interrupted_;
 
   bool potentially_animating_transform_for_active_observers_;
   bool potentially_animating_transform_for_pending_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerAnimationController);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_LAYER_ANIMATION_CONTROLLER_H_