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

cc/animation/property_animation_state.h

Index: cc/animation/property_animation_state.h
diff --git a/cc/animation/property_animation_state.h b/cc/animation/property_animation_state.h
index 74fbb699780fbed4671ad81fecefafb1e3e96dad..642576364e1f94005f68894083ea38575ad20107 100644
--- a/cc/animation/property_animation_state.h
+++ b/cc/animation/property_animation_state.h
@@ -5,21 +5,25 @@
 #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;