CC::Animations should use TimeTicks & TimeDelta to represent time

cc/animation/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_ANIMATION_EVENTS_H_
 #define CC_ANIMATION_ANIMATION_EVENTS_H_
 
 #include <vector>
 
 #include "cc/animation/animation.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/filter_operations.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 struct CC_EXPORT AnimationEvent {
   enum Type { Started, Finished, Aborted, PropertyUpdate };
 
   AnimationEvent(Type type,
                  int layer_id,
                  int group_id,
                  Animation::TargetProperty target_property,
-                 double monotonic_time);
+                 base::TimeTicks monotonic_time);
 
   Type type;
   int layer_id;
   int group_id;
   Animation::TargetProperty target_property;
-  double monotonic_time;
+  base::TimeTicks monotonic_time;
   bool is_impl_only;
   float opacity;
   gfx::Transform transform;
   FilterOperations filters;
 };
 
 typedef std::vector<AnimationEvent> AnimationEventsVector;
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ANIMATION_EVENTS_H_