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

cc/layers/scrollbar_layer_impl_base.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_IMPL_BASE_H_
+#define CC_LAYERS_SCROLLBAR_LAYER_IMPL_BASE_H_
+
+#include "cc/base/cc_export.h"
+#include "cc/input/scrollbar.h"
+#include "cc/layers/layer.h"
+#include "cc/layers/layer_impl.h"
+
+namespace cc {
+
+class LayerTreeImpl;
+
+class CC_EXPORT ScrollbarLayerImplBase : public LayerImpl {
+ public:
+  int scroll_layer_id() const { return scroll_layer_id_; }
+  void set_scroll_layer_id(int id) { scroll_layer_id_ = id; }
+
+  float CurrentPos() const { return current_pos_; }
+  void SetCurrentPos(float pos) { current_pos_ = pos; }
+  int Maximum() const { return maximum_; }
+  void SetMaximum(int maximum) { maximum_ = maximum; }
+
+  void set_visible_to_total_length_ratio(float ratio) {
+    visible_to_total_length_ratio_ = ratio;
+  }
+
+  void set_vertical_adjust(float vertical_adjust) {
+    vertical_adjust_ = vertical_adjust;
+  }
+
+  ScrollbarOrientation Orientation() const { return orientation_; }
+
+  virtual void PushPropertiesTo(LayerImpl* layer) OVERRIDE;
+  virtual ScrollbarLayerImplBase* ToScrollbarLayerBase() OVERRIDE;
+
+  virtual gfx::Rect ComputeThumbQuadRect() const = 0;
+
+ protected:
+  ScrollbarLayerImplBase(LayerTreeImpl* tree_impl,
+                         int id,
+                         ScrollbarOrientation orientation)
+      : LayerImpl(tree_impl, id),
+        scroll_layer_id_(Layer::INVALID_ID),
+        current_pos_(0.f),
+        maximum_(0),
+        orientation_(orientation),
+        visible_to_total_length_ratio_(1.f),
+        vertical_adjust_(0.f) {}
+  virtual ~ScrollbarLayerImplBase() {}
+
+  gfx::Rect ScrollbarLayerRectToContentRect(gfx::RectF layer_rect) const;
+  gfx::Rect ComputeThumbQuadRectInternal(int thumb_length,
+                                         float track_length,
+                                         int track_start,
+                                         int thumb_thickness) const;
+
+  int scroll_layer_id_;
+
+  float current_pos_;
+  int maximum_;
+  ScrollbarOrientation orientation_;
+
+  float visible_to_total_length_ratio_;
+  // Difference between the clip layer's height and the visible viewport
+  // height (which may differ in the presence of top-controls hiding).
+  float vertical_adjust_;
+};
+
+}  // namespace cc
+#endif  // CC_LAYERS_SCROLLBAR_LAYER_IMPL_BASE_H_