Refactor cc scrollbar layers to separate solid-color vs desktop.

cc/layers/scrollbar_layer.h

 // Copyright 2012 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_SCROLLBAR_LAYER_H_
 #define CC_LAYERS_SCROLLBAR_LAYER_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
 #include "cc/layers/contents_scaling_layer.h"
+#include "cc/layers/scrollbar_layer_interface.h"
 #include "cc/layers/scrollbar_theme_painter.h"
 #include "cc/resources/layer_updater.h"
 #include "cc/resources/scoped_ui_resource.h"
 
 namespace cc {
 class ScrollbarThemeComposite;
 
-class CC_EXPORT ScrollbarLayer : public ContentsScalingLayer {
+class CC_EXPORT ScrollbarLayer : public ScrollbarLayerInterface,
+                                 public ContentsScalingLayer {
  public:
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
       OVERRIDE;
 
   static scoped_refptr<ScrollbarLayer> Create(
       scoped_ptr<Scrollbar> scrollbar,
       int scroll_layer_id);
 
-  int scroll_layer_id() const { return scroll_layer_id_; }
-  void SetScrollLayerId(int id);
+  virtual bool OpacityCanAnimateOnImplThread() const OVERRIDE;
+  virtual ScrollbarLayerInterface* ToScrollbarLayer() OVERRIDE;
 
-  virtual bool OpacityCanAnimateOnImplThread() const OVERRIDE;
+  // ScrollbarLayerInterface
+  virtual int ScrollLayerId() const OVERRIDE;
+  virtual void SetScrollLayerId(int id) OVERRIDE;
 
-  ScrollbarOrientation Orientation() const;
+  virtual ScrollbarOrientation orientation() const OVERRIDE;
 
   // Layer interface
   virtual bool Update(ResourceUpdateQueue* queue,
                       const OcclusionTracker* occlusion) OVERRIDE;
   virtual void SetLayerTreeHost(LayerTreeHost* host) OVERRIDE;
   virtual void PushPropertiesTo(LayerImpl* layer) OVERRIDE;
   virtual void CalculateContentsScale(float ideal_contents_scale,
                                       float device_scale_factor,
                                       float page_scale_factor,
                                       bool animating_transform_to_screen,
                                       float* contents_scale_x,
                                       float* contents_scale_y,
                                       gfx::Size* content_bounds) OVERRIDE;
 
-  virtual ScrollbarLayer* ToScrollbarLayer() OVERRIDE;
-
  protected:
   ScrollbarLayer(scoped_ptr<Scrollbar> scrollbar, int scroll_layer_id);
   virtual ~ScrollbarLayer();
 
   // For unit tests
   UIResourceId track_resource_id() {
     return track_resource_.get() ? track_resource_->id() : 0;
   }
   UIResourceId thumb_resource_id() {
     return thumb_resource_.get() ? thumb_resource_->id() : 0;
   }
 
  private:
   gfx::Rect ScrollbarLayerRectToContentRect(gfx::Rect layer_rect) const;
   gfx::Rect OriginThumbRect() const;
 
   int MaxTextureSize();
   float ClampScaleToMaxTextureSize(float scale);
 
   scoped_refptr<UIResourceBitmap> RasterizeScrollbarPart(gfx::Rect rect,
                                                          ScrollbarPart part);
 
+  int scroll_layer_id_;
+
   scoped_ptr<Scrollbar> scrollbar_;
 
   int thumb_thickness_;
   int thumb_length_;
   gfx::Rect track_rect_;
-  int scroll_layer_id_;
 
   scoped_ptr<ScopedUIResource> track_resource_;
   scoped_ptr<ScopedUIResource> thumb_resource_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarLayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_SCROLLBAR_LAYER_H_