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

cc/layers/solid_color_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_SOLID_COLOR_SCROLLBAR_LAYER_H_
+#define CC_LAYERS_SOLID_COLOR_SCROLLBAR_LAYER_H_
+
+#include "cc/base/cc_export.h"
+#include "cc/layers/layer.h"
+#include "cc/layers/scrollbar_layer_interface.h"
+
+namespace cc {
+
+class CC_EXPORT SolidColorScrollbarLayer : public ScrollbarLayerInterface,
+                                           public Layer {
+ public:
+  virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
+      OVERRIDE;
+
+  static scoped_refptr<SolidColorScrollbarLayer> Create(
+      ScrollbarOrientation orientation,
+      int thumb_thickness,
+      int scroll_layer_id);
+
+  // Layer overrides.
+  virtual bool OpacityCanAnimateOnImplThread() const OVERRIDE;
+  virtual ScrollbarLayerInterface* ToScrollbarLayer() OVERRIDE;
+
+  // ScrollbarLayerInterface
+  virtual int ScrollLayerId() const OVERRIDE;
+  virtual void SetScrollLayerId(int id) OVERRIDE;
+
+  virtual ScrollbarOrientation orientation() const OVERRIDE;
+
+ protected:
+  SolidColorScrollbarLayer(ScrollbarOrientation orientation,
+                           int thumb_thickness,
+                           int scroll_layer_id);
+  virtual ~SolidColorScrollbarLayer();
+
+ private:
+  int scroll_layer_id_;
+  ScrollbarOrientation orientation_;
+  int thumb_thickness_;
+
+  DISALLOW_COPY_AND_ASSIGN(SolidColorScrollbarLayer);
+};
+
+}  // namespace cc
+
+#endif  // CC_LAYERS_SOLID_COLOR_SCROLLBAR_LAYER_H_