CC Animation: Use std::bitset to update animation state.

cc/animation/property_animation_state.h

 // Copyright 2016 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_PROPERTY_ANIMATION_STATE_H_
 #define CC_ANIMATION_PROPERTY_ANIMATION_STATE_H_
 
+#include "cc/animation/target_property.h"
 #include "cc/base/cc_export.h"
 
 namespace cc {
 
 struct CC_EXPORT PropertyAnimationState {
-  bool currently_running_for_active_elements = false;
-  bool currently_running_for_pending_elements = false;
-  bool potentially_animating_for_active_elements = false;
-  bool potentially_animating_for_pending_elements = false;
+  PropertyAnimationState();
+  PropertyAnimationState(const PropertyAnimationState& rhs);
+  ~PropertyAnimationState();
+
+  TargetProperties currently_running;
+  TargetProperties potentially_animating;
 
   bool operator==(const PropertyAnimationState& other) const;
   bool operator!=(const PropertyAnimationState& other) const;
 
   PropertyAnimationState& operator|=(const PropertyAnimationState& other);
   PropertyAnimationState& operator^=(const PropertyAnimationState& other);
+  PropertyAnimationState& operator&=(const PropertyAnimationState& other);
 
   bool IsValid() const;
 
   void Clear();
 };
 
 PropertyAnimationState operator^(const PropertyAnimationState& lhs,
                                  const PropertyAnimationState& rhs);
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_PROPERTY_ANIMATION_STATE_H_