Update PaintLayer::needsPaintPhaseXXX flags when add/remove layer on style change

third_party/WebKit/Source/core/paint/PaintLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 211 matching lines @@
     PaintLayer* firstChild() const { return m_first; }
     PaintLayer* lastChild() const { return m_last; }
 
     // TODO(wangxianzhu): Find a better name for it. 'paintContainer' might be good but
     // we can't use it for now because it conflicts with PaintInfo::paintContainer.
     PaintLayer* compositingContainer() const;
 
     void addChild(PaintLayer* newChild, PaintLayer* beforeChild = 0);
     PaintLayer* removeChild(PaintLayer*);
 
-    void removeOnlyThisLayer();
-    void insertOnlyThisLayer();
+    void removeOnlyThisLayerAfterStyleChange();
+    void insertOnlyThisLayerAfterStyleChange();
 
     void styleChanged(StyleDifference, const ComputedStyle* oldStyle);
 
     // FIXME: Many people call this function while it has out-of-date information.
     bool isSelfPaintingLayer() const { return m_isSelfPaintingLayer; }
 
     void setLayerType(PaintLayerType layerType) { m_layerType = layerType; ASSERT(static_cast<PaintLayerType>(m_layerType) == layerType); }
 
     bool isTransparent() const { return layoutObject()->isTransparent() || layoutObject()->style()->hasBlendMode() || layoutObject()->hasMask(); }
 
@@ skipping 419 matching lines @@
     void setPreviousPaintingClipRects(ClipRects& clipRects) { m_previousPaintingClipRects = &clipRects; }
 
     LayoutRect previousPaintDirtyRect() const { return m_previousPaintDirtyRect; }
     void setPreviousPaintDirtyRect(const LayoutRect& rect) { m_previousPaintDirtyRect = rect; }
 
     PaintLayerPainter::PaintResult previousPaintResult() const { return static_cast<PaintLayerPainter::PaintResult>(m_previousPaintResult); }
     void setPreviousPaintResult(PaintLayerPainter::PaintResult result) { m_previousPaintResult = static_cast<unsigned>(result); ASSERT(m_previousPaintResult == static_cast<unsigned>(result)); }
 
     // Used to skip PaintPhaseDescendantOutlinesOnly for layers that have never had descendant outlines.
     // Once it's set we never clear it because it's not easy to track if all outlines have been removed.
+    // For more details, see core/paint/REAME.md#Empty paint phase optimization.
     bool needsPaintPhaseDescendantOutlines() const { return m_needsPaintPhaseDescendantOutlines; }
     void setNeedsPaintPhaseDescendantOutlines() { ASSERT(isSelfPaintingLayer()); m_needsPaintPhaseDescendantOutlines = true; }
 
     // Similar to above, but for PaintPhaseFloat.
     bool needsPaintPhaseFloat() const { return m_needsPaintPhaseFloat; }
     void setNeedsPaintPhaseFloat() { ASSERT(isSelfPaintingLayer()); m_needsPaintPhaseFloat = true; }
 
     bool needsPaintPhaseDescendantBlockBackgrounds() const { return m_needsPaintPhaseDescendantBlockBackgrounds; }
     void setNeedsPaintPhaseDescendantBlockBackgrounds() { ASSERT(isSelfPaintingLayer()); m_needsPaintPhaseDescendantBlockBackgrounds = true; }
 
@@ skipping 82 matching lines @@
 
     void markCompositingContainerChainForNeedsRepaint();
 
     PaintLayerRareData& ensureRareData()
     {
         if (!m_rareData)
             m_rareData = adoptPtr(new PaintLayerRareData);
         return *m_rareData;
     }
 
+    void mergeNeedsPaintPhaseFlagsFrom(const PaintLayer& layer)
+    {
+        m_needsPaintPhaseDescendantOutlines |= layer.m_needsPaintPhaseDescendantOutlines;
+        m_needsPaintPhaseFloat |= layer.m_needsPaintPhaseFloat;
+        m_needsPaintPhaseDescendantBlockBackgrounds |= layer.m_needsPaintPhaseDescendantBlockBackgrounds;
+    }
+
     unsigned m_layerType : 2; // PaintLayerType
 
     // Self-painting layer is an optimization where we avoid the heavy Layer painting
     // machinery for a Layer allocated only to handle the overflow clip case.
     // FIXME(crbug.com/332791): Self-painting layer should be merged into the overflow-only concept.
     unsigned m_isSelfPaintingLayer : 1;
 
     // If have no self-painting descendants, we don't have to walk our children during painting. This can lead to
     // significant savings, especially if the tree has lots of non-self-painting layers grouped together (e.g. table cells).
     mutable unsigned m_hasSelfPaintingLayerDescendant : 1;
@@ skipping 89 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::PaintLayer*);
 void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif // Layer_h