Separate display item clients for negative and normal/positive z-order children

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 5477d3a81f1966c9fc45e4b5aa0605a44b86e2ed..19e7b78bcd21df98320cd3c40e7caf0cfd83fd83 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -467,25 +467,20 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintChildren(unsigned childre
     if (!child)
         return result;
 
-    DisplayItem::Type subsequenceType;
-    if (childrenToVisit == NegativeZOrderChildren) {
-        subsequenceType = DisplayItem::SubsequenceNegativeZOrder;
-    } else {
-        ASSERT(childrenToVisit == (NormalFlowChildren | PositiveZOrderChildren));
-        subsequenceType = DisplayItem::SubsequenceNormalFlowAndPositiveZOrder;
-    }
-
     Optional<SubsequenceRecorder> subsequenceRecorder;
     if (!paintingInfo.disableSubsequenceCache
         && !context->printing()
         && m_paintLayer.stackingNode()->isStackingContext()
         && !(paintingInfo.globalPaintFlags() & GlobalPaintFlattenCompositingLayers)
         && !(paintFlags & (PaintLayerPaintingReflection | PaintLayerPaintingRootBackgroundOnly | PaintLayerPaintingOverlayScrollbars))) {
+        ASSERT(childrenToVisit == NegativeZOrderChildren || childrenToVisit == (NormalFlowChildren | PositiveZOrderChildren));
+        DisplayItemClientWrapper displayItemClient(childrenToVisit == NegativeZOrderChildren ? m_paintLayer.displayItemClientForNegativeZOrderChildren() : m_paintLayer.displayItemClientForNormalAndPositiveZOrderChildren());
         if (!m_paintLayer.needsRepaint()
             && paintingInfo.scrollOffsetAccumulation == m_paintLayer.previousScrollOffsetAccumulationForPainting()
-            && SubsequenceRecorder::useCachedSubsequenceIfPossible(*context, m_paintLayer, subsequenceType))
+            && SubsequenceRecorder::useCachedSubsequenceIfPossible(*context, displayItemClient)) {
             return result;
-        subsequenceRecorder.emplace(*context, m_paintLayer, subsequenceType);
+        }
+        subsequenceRecorder.emplace(*context, displayItemClient);
     }
 
     IntSize scrollOffsetAccumulationForChildren = paintingInfo.scrollOffsetAccumulation;