cc: Cleanup class/struct forward declarations

cc/layers/painted_scrollbar_layer.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_LAYERS_PAINTED_SCROLLBAR_LAYER_H_
 #define CC_LAYERS_PAINTED_SCROLLBAR_LAYER_H_
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/scrollbar_layer_interface.h"
 #include "cc/layers/scrollbar_theme_painter.h"
 #include "cc/resources/scoped_ui_resource.h"
 
 namespace cc {
-class ScrollbarThemeComposite;
 
 class CC_EXPORT PaintedScrollbarLayer : public ScrollbarLayerInterface,
                                         public Layer {
  public:
   std::unique_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
 
   static scoped_refptr<PaintedScrollbarLayer> Create(
       std::unique_ptr<Scrollbar> scrollbar,
       int scroll_layer_id);
 
@@ skipping 67 matching lines @@
   std::unique_ptr<ScopedUIResource> thumb_resource_;
 
   float thumb_opacity_;
 
   DISALLOW_COPY_AND_ASSIGN(PaintedScrollbarLayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PAINTED_SCROLLBAR_LAYER_H_