Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

cc/pinch_zoom_scrollbar_painter.h

Index: cc/pinch_zoom_scrollbar_painter.h
diff --git a/cc/pinch_zoom_scrollbar_painter.h b/cc/pinch_zoom_scrollbar_painter.h
new file mode 100644
index 0000000000000000000000000000000000000000..0a7cd586991fb93e397f4d3e5971c6b92c527ac8
--- /dev/null
+++ b/cc/pinch_zoom_scrollbar_painter.h
@@ -0,0 +1,32 @@
+// 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_PINCH_ZOOM_SCROLLBAR_PAINTER_H_
+#define CC_PINCH_ZOOM_SCROLLBAR_PAINTER_H_
+
+#include "base/compiler_specific.h"
+#include "cc/scrollbar_theme_painter.h"
+
+namespace cc {
+
+class PinchZoomScrollbarPainter : public ScrollbarThemePainter {
+ public:
+  PinchZoomScrollbarPainter() {}
+  virtual ~PinchZoomScrollbarPainter();
+
+  virtual void PaintScrollbarBackground(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintTrackBackground(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintBackTrackPart(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintForwardTrackPart(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintBackButtonStart(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintBackButtonEnd(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintForwardButtonStart(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintForwardButtonEnd(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintTickmarks(SkCanvas*, const gfx::Rect&) OVERRIDE;
+  virtual void PaintThumb(SkCanvas*, const gfx::Rect&) OVERRIDE;
+};
+
+}  // namespace cc
+
+#endif  // CC_PINCH_ZOOM_SCROLLBAR_PAINTER_H_