Factor painting code out of RenderBox into a new class called BoxPainter.

Source/core/paint/BoxDecorationData.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 BoxDecorationData_h
+#define BoxDecorationData_h
+
+#include "core/rendering/RenderBoxModelObject.h"
+#include "platform/graphics/Color.h"
+
+namespace blink {
+
+class RenderStyle;
+class GraphicsContext;
+
+// Information extracted from RenderStyle for box painting.
+class BoxDecorationData {
+public:
+    BoxDecorationData(const RenderStyle&, bool canRenderBorderImage, bool backgroundHasOpaqueTopLayer, GraphicsContext*);
+
+    Color backgroundColor;
+    bool hasBackground;
+    bool hasBorder;
+    bool hasAppearance;
+    BackgroundBleedAvoidance bleedAvoidance() { return static_cast<BackgroundBleedAvoidance>(m_bleedAvoidance); }
+
+private:
+    BackgroundBleedAvoidance determineBackgroundBleedAvoidance(const RenderStyle&, bool canRenderBorderImage, bool backgroundHasOpaqueTopLayer, GraphicsContext*);
+    bool borderObscuresBackgroundEdge(const RenderStyle&, const FloatSize& contextScale) const;
+    unsigned m_bleedAvoidance : 2; // BackgroundBleedAvoidance
+};
+
+} // namespace blink
+
+#endif