cc: Cleanup class/struct forward declarations

cc/animation/element_animations.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_ELEMENT_ANIMATIONS_H_
 #define CC_ANIMATION_ELEMENT_ANIMATIONS_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
 #include "cc/trees/element_id.h"
 #include "cc/trees/property_animation_state.h"
 #include "cc/trees/target_property.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/transform.h"
 
 namespace gfx {
 class BoxF;
 }
 
 namespace cc {
 
-class AnimationDelegate;
 class AnimationEvents;
 class AnimationHost;
 class AnimationPlayer;
 class FilterOperations;
 enum class ElementListType;
 struct AnimationEvent;
 
 // An ElementAnimations owns a list of all AnimationPlayers, attached to
 // the element.
 // This is a CC counterpart for blink::ElementAnimations (in 1:1 relationship).
@@ skipping 180 matching lines @@
   PropertyAnimationState pending_state_;
 
   bool needs_update_impl_client_state_;
 
   DISALLOW_COPY_AND_ASSIGN(ElementAnimations);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ELEMENT_ANIMATIONS_H_