Paint local attachment backgrounds into composited scrolling contents layer

third_party/WebKit/Source/core/style/FillLayer.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 298 matching lines @@
     for (FillLayer* p = this; p; p = next) {
         next = p->m_next;
         if (next && !next->isImageSet()) {
             delete next;
             p->m_next = 0;
             break;
         }
     }
 }
 
-static EFillBox clipMax(EFillBox clipA, EFillBox clipB)
-{
-    if (clipA == BorderFillBox || clipB == BorderFillBox)
-        return BorderFillBox;
-    if (clipA == PaddingFillBox || clipB == PaddingFillBox)
-        return PaddingFillBox;
-    if (clipA == ContentFillBox || clipB == ContentFillBox)
-        return ContentFillBox;
-    return TextFillBox;
-}
-
 void FillLayer::computeCachedPropertiesIfNeeded() const
 {
     if (m_cachedPropertiesComputed)
         return;
     m_thisOrNextLayersClipMax = clip();
     m_thisOrNextLayersUseContentBox = clip() == ContentFillBox || origin() == ContentFillBox;
     m_thisOrNextLayersHaveLocalAttachment = attachment() == LocalBackgroundAttachment;
     m_cachedPropertiesComputed = true;
 
     if (m_next) {
         m_next->computeCachedPropertiesIfNeeded();
-        m_thisOrNextLayersClipMax = clipMax(thisOrNextLayersClipMax(), m_next->thisOrNextLayersClipMax());
+        m_thisOrNextLayersClipMax = enclosingFillBox(thisOrNextLayersClipMax(), m_next->thisOrNextLayersClipMax());
         m_thisOrNextLayersUseContentBox |= m_next->m_thisOrNextLayersUseContentBox;
         m_thisOrNextLayersHaveLocalAttachment |= m_next->m_thisOrNextLayersHaveLocalAttachment;
     }
 }
 
 bool FillLayer::clipOccludesNextLayers() const
 {
     return clip() == thisOrNextLayersClipMax();
 }
 
@@ skipping 67 matching lines @@
 {
     for (; layer1 && layer2; layer1 = layer1->next(), layer2 = layer2->next()) {
         if (!layerImagesIdentical(*layer1, *layer2))
             return false;
     }
 
     return !layer1 && !layer2;
 }
 
 } // namespace blink