Re-introduce forward declaration of WebCompositorAnimation

cc/blink/web_animation_impl.h

 // Copyright 2014 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_BLINK_WEB_ANIMATION_IMPL_H_
 #define CC_BLINK_WEB_ANIMATION_IMPL_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/blink/cc_blink_export.h"
 #include "third_party/WebKit/public/platform/WebCompositorAnimation.h"
-#include "third_party/WebKit/public/platform/WebCompositorAnimationCurve.h"
 
 namespace cc {
 class Animation;
 }
 
+namespace blink {
+class WebCompositorAnimationCurve;
+}
+
 namespace cc_blink {
 
 class WebCompositorAnimationImpl : public blink::WebCompositorAnimation {
  public:
   CC_BLINK_EXPORT WebCompositorAnimationImpl(
       const blink::WebCompositorAnimationCurve& curve,
       TargetProperty target,
       int animation_id,
       int group_id);
   virtual ~WebCompositorAnimationImpl();
@@ skipping 24 matching lines @@
 
  private:
   scoped_ptr<cc::Animation> animation_;
 
   DISALLOW_COPY_AND_ASSIGN(WebCompositorAnimationImpl);
 };
 
 }  // namespace cc_blink
 
 #endif  // CC_BLINK_WEB_ANIMATION_IMPL_H_