Add viewport scrollbar class to support overlay scrollbars for pinch zoom virtual viewport.

cc/input/viewport_scrollbar.h

-// Copyright 2012 The Chromium Authors. All rights reserved.
+// 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_TEST_FAKE_SCROLLBAR_H_
-#define CC_TEST_FAKE_SCROLLBAR_H_
+#ifndef CC_INPUT_VIEWPORT_SCROLLBAR_H_
+#define CC_INPUT_VIEWPORT_SCROLLBAR_H_
 
-#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
-#include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/point.h"
+#include "ui/gfx/rect.h"
 
 namespace cc {
 
-class FakeScrollbar : public Scrollbar {
+class Layer;
+
+class CC_EXPORT ViewportScrollbar : public Scrollbar {
  public:
-  FakeScrollbar();
-  FakeScrollbar(bool paint, bool has_thumb, bool is_overlay);
-  virtual ~FakeScrollbar();
+  ViewportScrollbar(scoped_refptr<Layer> scroll_layer,
+                    ScrollbarOrientation orientation,
+                    size_t thickness);
+  virtual ~ViewportScrollbar();
 
-  // Scrollbar implementation.
   virtual ScrollbarOrientation Orientation() const OVERRIDE;
   virtual gfx::Point Location() const OVERRIDE;
   virtual bool IsOverlay() const OVERRIDE;
   virtual bool HasThumb() const OVERRIDE;
   virtual int ThumbThickness() const OVERRIDE;
   virtual int ThumbLength() const OVERRIDE;
   virtual gfx::Rect TrackRect() const OVERRIDE;
   virtual void PaintPart(SkCanvas* canvas,
                          ScrollbarPart part,
                          gfx::Rect content_rect) OVERRIDE;
 
-  void set_location(gfx::Point location) { location_ = location; }
-
  private:
-  bool paint_;
-  bool has_thumb_;
-  bool is_overlay_;
-  gfx::Point location_;
-  SkColor fill_color_;
-
-  DISALLOW_COPY_AND_ASSIGN(FakeScrollbar);
+  scoped_refptr<Layer> scroll_layer_;
+  ScrollbarOrientation orientation_;
+  const size_t thickness_;
 };
 
 }  // namespace cc
 
-#endif  // CC_TEST_FAKE_SCROLLBAR_H_
+#endif  // CC_INPUT_VIEWPORT_SCROLLBAR_H_