CC Animation: Move ElementId from animation to trees.

cc/animation/animation_player.h

 // Copyright 2015 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_PLAYER_H_
 #define CC_ANIMATION_ANIMATION_PLAYER_H_
 
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/element_animations.h"
-#include "cc/animation/element_id.h"
 #include "cc/base/cc_export.h"
+#include "cc/trees/element_id.h"
 
 namespace cc {
 
 class AnimationDelegate;
 class AnimationHost;
 class AnimationTimeline;
 struct AnimationEvent;
 struct PropertyAnimationState;
 
 // An AnimationPlayer owns all animations to be run on particular CC Layer.
@@ skipping 165 matching lines @@
   // Only try to start animations when new animations are added or when the
   // previous attempt at starting animations failed to start all animations.
   bool needs_to_start_animations_;
 
   DISALLOW_COPY_AND_ASSIGN(AnimationPlayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ANIMATION_PLAYER_H_