Allow impl-only animations, and return opacity values via AnimationEvents.

cc/animation_events.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_EVENTS_H_
 #define CC_ANIMATION_EVENTS_H_
 
 #include <vector>
 
 #include "cc/animation.h"
+#include "ui/gfx/transform.h"
 
 namespace cc {
 
 struct AnimationEvent {
-    enum Type { Started, Finished };
+    enum Type { Started, Finished, PropertyUpdate };
 
     AnimationEvent(Type type, int layerId, int groupId, Animation::TargetProperty targetProperty, double monotonicTime)
         : type(type)
         , layerId(layerId)
         , groupId(groupId)
         , targetProperty(targetProperty)
         , monotonicTime(monotonicTime)
+        , opacity(0)
     {
     }
 
     Type type;
     int layerId;
     int groupId;
     Animation::TargetProperty targetProperty;
     double monotonicTime;
+    float opacity;
+    gfx::Transform transform;
 };
 
 typedef std::vector<AnimationEvent> AnimationEventsVector;
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_EVENTS_H_