Factor painting code from RenderLayerScrollableArea into ScrollableAreaPainter

Source/core/paint/PartPainter.cpp

 // 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.
 
 #include "config.h"
 #include "core/paint/PartPainter.h"
 
 #include "core/paint/BoxPainter.h"
 
+#include "core/paint/ScrollableAreaPainter.h"
 #include "core/rendering/GraphicsContextAnnotator.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderPart.h"
 
 namespace blink {
 
 void PartPainter::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     ANNOTATE_GRAPHICS_CONTEXT(paintInfo, &m_renderPart);
@@ skipping 37 matching lines @@
         paintInfo.context->restore();
 
     // Paint a partially transparent wash over selected widgets.
     if (m_renderPart.isSelected() && !m_renderPart.document().printing()) {
         LayoutRect rect = m_renderPart.localSelectionRect();
         rect.moveBy(adjustedPaintOffset);
         paintInfo.context->fillRect(pixelSnappedIntRect(rect), m_renderPart.selectionBackgroundColor());
     }
 
     if (m_renderPart.canResize())
-        m_renderPart.layer()->scrollableArea()->paintResizer(paintInfo.context, roundedIntPoint(adjustedPaintOffset), paintInfo.rect);
+        ScrollableAreaPainter(*m_renderPart.layer()->scrollableArea()).paintResizer(paintInfo.context, roundedIntPoint(adjustedPaintOffset), paintInfo.rect);
 }
 
 void PartPainter::paintContents(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     LayoutPoint adjustedPaintOffset = paintOffset + m_renderPart.location();
 
     Widget* widget = m_renderPart.widget();
     RELEASE_ASSERT(widget);
 
     // Tell the widget to paint now. This is the only time the widget is allowed
@@ skipping 10 matching lines @@
         paintInfo.context->translate(widgetPaintOffset.width(), widgetPaintOffset.height());
         paintRect.move(-widgetPaintOffset);
     }
     widget->paint(paintInfo.context, paintRect);
 
     if (!widgetPaintOffset.isZero())
         paintInfo.context->translate(-widgetPaintOffset.width(), -widgetPaintOffset.height());
 }
 
 } // namespace blink