CC Animation: Move ElementId from animation to trees.

cc/trees/mutator_host.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_TREES_MUTATOR_HOST_H_
 #define CC_TREES_MUTATOR_HOST_H_
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/time/time.h"
-#include "cc/animation/element_id.h"
+#include "cc/trees/element_id.h"
 #include "cc/trees/mutator_host_client.h"
 #include "ui/gfx/geometry/box_f.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace gfx {
 class ScrollOffset;
 }
 
 namespace cc {
 
@@ skipping 106 matching lines @@
 
 class MutatorEvents {
  public:
   virtual ~MutatorEvents() {}
   virtual bool IsEmpty() const = 0;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_MUTATOR_HOST_H_