Reland of Skip PaintLayer empty paint phases if it previously painted nothing

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 663 matching lines @@
     ClipRects* previousPaintingClipRects() const { return m_previousPaintingClipRects.get(); }
     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.
+    // The flag is set during paint invalidation on a self painting layer if any contained object has outline.
+    // It's cleared during painting if PaintPhaseDescendantOutlinesOnly painted nothing.
     // 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; }
+    bool needsPaintPhaseDescendantOutlines() const { return m_needsPaintPhaseDescendantOutlines && !m_previousPaintPhaseDescendantOutlinesWasEmpty; }
+    void setNeedsPaintPhaseDescendantOutlines()
+    {
+        DCHECK(isSelfPaintingLayer());
+        m_needsPaintPhaseDescendantOutlines = true;
+        m_previousPaintPhaseDescendantOutlinesWasEmpty = false;
+    }
+    void setPreviousPaintPhaseDescendantOutlinesEmpty(bool isEmpty) { m_previousPaintPhaseDescendantOutlinesWasEmpty = isEmpty; }
 
     // Similar to above, but for PaintPhaseFloat.
-    bool needsPaintPhaseFloat() const { return m_needsPaintPhaseFloat; }
-    void setNeedsPaintPhaseFloat() { ASSERT(isSelfPaintingLayer()); m_needsPaintPhaseFloat = true; }
+    bool needsPaintPhaseFloat() const { return m_needsPaintPhaseFloat && !m_previousPaintPhaseFloatWasEmpty; }
+    void setNeedsPaintPhaseFloat()
+    {
+        DCHECK(isSelfPaintingLayer());
+        m_needsPaintPhaseFloat = true;
+        m_previousPaintPhaseFloatWasEmpty = false;
+    }
+    void setPreviousPaintPhaseFloatEmpty(bool isEmpty) { m_previousPaintPhaseFloatWasEmpty= isEmpty; }
 
-    bool needsPaintPhaseDescendantBlockBackgrounds() const { return m_needsPaintPhaseDescendantBlockBackgrounds; }
-    void setNeedsPaintPhaseDescendantBlockBackgrounds() { ASSERT(isSelfPaintingLayer()); m_needsPaintPhaseDescendantBlockBackgrounds = true; }
+    // Similar to above, but for PaintPhaseDescendantBlockBackgroundsOnly.
+    bool needsPaintPhaseDescendantBlockBackgrounds() const { return m_needsPaintPhaseDescendantBlockBackgrounds && !m_previousPaintPhaseDescendantBlockBackgroundsWasEmpty; }
+    void setNeedsPaintPhaseDescendantBlockBackgrounds()
+    {
+        DCHECK(isSelfPaintingLayer());
+        m_needsPaintPhaseDescendantBlockBackgrounds = true;
+        m_previousPaintPhaseDescendantBlockBackgroundsWasEmpty = false;
+    }
+    void setPreviousPaintPhaseDescendantBlockBackgroundsEmpty(bool isEmpty) { m_previousPaintPhaseDescendantBlockBackgroundsWasEmpty = isEmpty; }
 
     PaintTiming* paintTiming();
 
     ClipRectsCache* clipRectsCache() const { return m_clipRectsCache.get(); }
     ClipRectsCache& ensureClipRectsCache() const
     {
         if (!m_clipRectsCache)
             m_clipRectsCache = wrapUnique(new ClipRectsCache);
         return *m_clipRectsCache;
     }
@@ skipping 139 matching lines @@
     unsigned m_shouldIsolateCompositedDescendants : 1;
 
     // True if this layout layer just lost its grouped mapping due to the CompositedLayerMapping being destroyed,
     // and we don't yet know to what graphics layer this Layer will be assigned.
     unsigned m_lostGroupedMapping : 1;
 
     unsigned m_needsRepaint : 1;
     unsigned m_previousPaintResult : 1; // PaintLayerPainter::PaintResult
 
     unsigned m_needsPaintPhaseDescendantOutlines : 1;
+    unsigned m_previousPaintPhaseDescendantOutlinesWasEmpty : 1;
     unsigned m_needsPaintPhaseFloat : 1;
+    unsigned m_previousPaintPhaseFloatWasEmpty : 1;
     unsigned m_needsPaintPhaseDescendantBlockBackgrounds : 1;
+    unsigned m_previousPaintPhaseDescendantBlockBackgroundsWasEmpty : 1;
 
     // These bitfields are part of ancestor/descendant dependent compositing inputs.
     unsigned m_hasDescendantWithClipPath : 1;
     unsigned m_hasNonIsolatedDescendantWithBlendMode : 1;
     unsigned m_hasAncestorWithClipPath : 1;
 
     LayoutBoxModelObject* m_layoutObject;
 
     PaintLayer* m_parent;
     PaintLayer* m_previous;
@@ skipping 35 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