Re-introduce forward declaration of WebCompositorAnimation

cc/blink/web_to_cc_animation_delegate_adapter.cc

 // 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.
 
 #include "cc/blink/web_to_cc_animation_delegate_adapter.h"
+#include "third_party/WebKit/public/platform/WebCompositorAnimationDelegate.h"
 
 namespace cc_blink {
 
 WebToCCAnimationDelegateAdapter::WebToCCAnimationDelegateAdapter(
     blink::WebCompositorAnimationDelegate* delegate)
     : delegate_(delegate) {
 }
 
 void WebToCCAnimationDelegateAdapter::NotifyAnimationStarted(
     base::TimeTicks monotonic_time,
     cc::Animation::TargetProperty target_property) {
   delegate_->notifyAnimationStarted(
       (monotonic_time - base::TimeTicks()).InSecondsF(),
       static_cast<blink::WebCompositorAnimation::TargetProperty>(
           target_property));
 }
 
 void WebToCCAnimationDelegateAdapter::NotifyAnimationFinished(
     base::TimeTicks monotonic_time,
     cc::Animation::TargetProperty target_property) {
   delegate_->notifyAnimationFinished(
       (monotonic_time - base::TimeTicks()).InSecondsF(),
       static_cast<blink::WebCompositorAnimation::TargetProperty>(
           target_property));
 }
 
 }  // namespace cc_blink