content: Cleanup class/struct forward declarations

content/browser/web_contents/aura/overscroll_window_animation.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 CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_ANIMATION_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_ANIMATION_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
 #include "content/common/content_export.h"
 #include "ui/compositor/layer_animation_observer.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ui {
 class Layer;
-class LayerAnimator;
 }
 
 namespace content {
 
 class ShadowLayerDelegate;
-class WebContentsImpl;
 
 // Manages the animation of a window sliding on top or behind another one. The
 // main window, which is the one displayed before the animation starts, is not
 // owned by OverscrollWindowAnimation, while the slide window, created at the
 // start of the animation, is owned by us for its duration.
 class CONTENT_EXPORT OverscrollWindowAnimation
     : public OverscrollControllerDelegate,
       ui::ImplicitAnimationObserver {
  public:
   // The direction of this animation. SLIDE_FRONT indicates that the slide
@@ skipping 86 matching lines @@
   // Indicates if the current slide has been cancelled. True while the cancel
   // animation is in progress.
   bool overscroll_cancelled_;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollWindowAnimation);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_ANIMATION_H_