Revert of Optimize the pre-paint tree walk and ClipRects

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

Index: third_party/WebKit/Source/core/paint/PaintLayer.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.h b/third_party/WebKit/Source/core/paint/PaintLayer.h
index fb3c6e80fca416c9738b9ebb6f885aeac137b36f..988052902d4b1a9057e26adad6be02955f93750f 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.h
@@ -901,17 +901,11 @@
     m_previousScrollOffsetAccumulationForPainting = s;
   }
 
-  bool hasPreviousPaintingClipRects() const {
-    return m_hasPreviousPaintingClipRects;
-  }
-
-  const ClipRects& previousPaintingClipRects() const {
-    return m_previousPaintingClipRects;
-  }
-
-  void setPreviousPaintingClipRects(const ClipRects& clipRects) {
-    m_previousPaintingClipRects = clipRects;
-    m_hasPreviousPaintingClipRects = true;
+  ClipRects* previousPaintingClipRects() const {
+    return m_previousPaintingClipRects.get();
+  }
+  void setPreviousPaintingClipRects(ClipRects& clipRects) {
+    m_previousPaintingClipRects = &clipRects;
   }
 
   LayoutRect previousPaintDirtyRect() const { return m_previousPaintDirtyRect; }
@@ -1206,8 +1200,6 @@
 
   unsigned m_selfPaintingStatusChanged : 1;
 
-  unsigned m_hasPreviousPaintingClipRects : 1;
-
   LayoutBoxModelObject& m_layoutObject;
 
   PaintLayer* m_parent;
@@ -1243,7 +1235,7 @@
   std::unique_ptr<PaintLayerStackingNode> m_stackingNode;
 
   IntSize m_previousScrollOffsetAccumulationForPainting;
-  ClipRects m_previousPaintingClipRects;
+  RefPtr<ClipRects> m_previousPaintingClipRects;
   LayoutRect m_previousPaintDirtyRect;
 
   std::unique_ptr<PaintLayerRareData> m_rareData;