Paint local attachment backgrounds into composited scrolling contents layer

third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
index 3b685597d828d7be414c0362dd314c82aad40ff1..5e5909494d65375de366f5f0a2a33474422d40f0 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -265,6 +265,7 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContents(GraphicsCon
     bool isPaintingCompositedForeground = paintFlags & PaintLayerPaintingCompositingForegroundPhase;
     bool isPaintingCompositedBackground = paintFlags & PaintLayerPaintingCompositingBackgroundPhase;
     bool isPaintingOverflowContents = paintFlags & PaintLayerPaintingOverflowContents;
+    bool isPaintingBackgroundOntoForeground = paintFlags & PaintLayerPaintingBackgroundOntoForeground;
     // Outline always needs to be painted even if we have no visible content. Also,
     // the outline is painted in the background phase during composited scrolling.
     // If it were painted in the foreground phase, it would move with the scrolled
@@ -381,7 +382,9 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContents(GraphicsCon
             scopedPaintChunkProperties.emplace(context.getPaintController(), m_paintLayer, properties);
         }
 
-        bool shouldPaintBackground = isPaintingCompositedBackground && shouldPaintContent && !selectionOnly;
+        bool shouldPaintBackground = shouldPaintContent && !selectionOnly
+            && ((isPaintingBackgroundOntoForeground && isPaintingCompositedForeground)
+                || isPaintingCompositedBackground);
         bool shouldPaintNegZOrderList = (isPaintingScrollingContent && isPaintingOverflowContents) || (!isPaintingScrollingContent && isPaintingCompositedBackground);
         bool shouldPaintOwnContents = isPaintingCompositedForeground && shouldPaintContent;
         bool shouldPaintNormalFlowAndPosZOrderLists = isPaintingCompositedForeground;