Factor painting code from RenderLayerScrollableArea into ScrollableAreaPainter

Source/core/paint/ScrollableAreaPainter.h

+// Copyright 2014 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 ScrollableAreaPainter_h
+#define ScrollableAreaPainter_h
+
+namespace blink {
+
+class GraphicsContext;
+class IntPoint;
+class IntRect;
+class RenderLayerScrollableArea;
+
+class ScrollableAreaPainter {
+public:
+    ScrollableAreaPainter(RenderLayerScrollableArea& renderLayerScrollableArea) : m_renderLayerScrollableArea(renderLayerScrollableArea) { }
+
+    void paintResizer(GraphicsContext*, const IntPoint& paintOffset, const IntRect& damageRect);
+    void paintOverflowControls(GraphicsContext*, const IntPoint& paintOffset, const IntRect& damageRect, bool paintingOverlayControls);
+    void paintScrollCorner(GraphicsContext*, const IntPoint&, const IntRect& damageRect);
+
+private:
+    void drawPlatformResizerImage(GraphicsContext*, IntRect resizerCornerRect);
+    bool overflowControlsIntersectRect(const IntRect& localRect) const;
+
+    RenderLayerScrollableArea& m_renderLayerScrollableArea;
+};
+
+} // namespace blink
+
+#endif // ScrollableAreaPainter_h