Paint solid color backgrounds which are equivalent to locally attached into scrolling contents layer

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 163 matching lines @@
     // This will work on inlines to return the bounding box of all of the lines' border boxes.
     virtual IntRect borderBoundingBox() const = 0;
 
     virtual LayoutRect visualOverflowRect() const = 0;
 
     // Checks if this box, or any of it's descendants, or any of it's continuations,
     // will take up space in the layout of the page.
     bool hasNonEmptyLayoutSize() const;
     bool usesCompositedScrolling() const;
 
+    // Checks if all of the background's layers can be painted as locally
+    // attached.
+    bool hasLocalEquivalentBackground() const;
+
     // These return the CSS computed padding values.
     LayoutUnit computedCSSPaddingTop() const { return computedCSSPadding(style()->paddingTop()); }
     LayoutUnit computedCSSPaddingBottom() const { return computedCSSPadding(style()->paddingBottom()); }
     LayoutUnit computedCSSPaddingLeft() const { return computedCSSPadding(style()->paddingLeft()); }
     LayoutUnit computedCSSPaddingRight() const { return computedCSSPadding(style()->paddingRight()); }
     LayoutUnit computedCSSPaddingBefore() const { return computedCSSPadding(style()->paddingBefore()); }
     LayoutUnit computedCSSPaddingAfter() const { return computedCSSPadding(style()->paddingAfter()); }
     LayoutUnit computedCSSPaddingStart() const { return computedCSSPadding(style()->paddingStart()); }
     LayoutUnit computedCSSPaddingEnd() const { return computedCSSPadding(style()->paddingEnd()); }
     LayoutUnit computedCSSPaddingOver() const { return computedCSSPadding(style()->paddingOver()); }
@@ skipping 182 matching lines @@
     std::unique_ptr<PaintLayer> m_layer;
 
     std::unique_ptr<LayoutBoxModelObjectRareData> m_rareData;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBoxModelObject, isBoxModelObject());
 
 } // namespace blink
 
 #endif // LayoutBoxModelObject_h