Impl thread smooth scrolling.

cc/animation/animation_delegate.h

 // Copyright 2013 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_DELEGATE_H_
 #define CC_ANIMATION_ANIMATION_DELEGATE_H_
 
 #include "base/time/time.h"
 #include "cc/animation/animation.h"
 
 namespace cc {
 
-class AnimationDelegate {
+class CC_EXPORT AnimationDelegate {
  public:
   virtual void NotifyAnimationStarted(
       base::TimeTicks monotonic_time,
       Animation::TargetProperty target_property) = 0;
   virtual void NotifyAnimationFinished(
       base::TimeTicks monotonic_time,
       Animation::TargetProperty target_property) = 0;
 
  protected:
   virtual ~AnimationDelegate() {}
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ANIMATION_DELEGATE_H_