CC Animation: Move ElementId from animation to trees.

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 <memory>
 #include <vector>
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_curve.h"
-#include "cc/animation/element_id.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/filter_operations.h"
+#include "cc/trees/element_id.h"
 #include "cc/trees/mutator_host.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 struct CC_EXPORT AnimationEvent {
   enum Type { STARTED, FINISHED, ABORTED, PROPERTY_UPDATE, TAKEOVER };
 
   AnimationEvent(Type type,
                  ElementId element_id,
@@ skipping 28 matching lines @@
   // MutatorEvents implementation.
   ~AnimationEvents() override;
   bool IsEmpty() const override;
 
   std::vector<AnimationEvent> events_;
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ANIMATION_EVENTS_H_