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

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

 // 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.
 
 #include "config.h"
 #include "core/paint/PaintLayerPainter.h"
 
 #include "core/frame/Settings.h"
 #include "core/layout/ClipPathOperation.h"
 #include "core/layout/LayoutBlock.h"
@@ skipping 449 matching lines @@
 
 #if ENABLE(ASSERT)
     LayerListMutationDetector mutationChecker(m_paintLayer.stackingNode());
 #endif
 
     PaintLayerStackingNodeIterator iterator(*m_paintLayer.stackingNode(), childrenToVisit);
     PaintLayerStackingNode* child = iterator.next();
     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;
     if (m_paintLayer.layoutObject()->hasOverflowClip())
         scrollOffsetAccumulationForChildren += m_paintLayer.layoutBox()->scrolledContentOffset();
 
     bool disableChildSubsequenceCache = !RuntimeEnabledFeatures::slimmingPaintV2Enabled()
         && (m_paintLayer.layoutObject()->hasOverflowClip() || m_paintLayer.layoutObject()->hasClip());
 
     for (; child; child = iterator.next()) {
@@ skipping 195 matching lines @@
     if (!m_paintLayer.containsDirtyOverlayScrollbars())
         return;
 
     PaintLayerPaintingInfo paintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(damageRect)), paintFlags, LayoutSize(), paintingRoot);
     paintLayer(context, paintingInfo, PaintLayerPaintingOverlayScrollbars);
 
     m_paintLayer.setContainsDirtyOverlayScrollbars(false);
 }
 
 } // namespace blink