Move all descendant-dependent flags into the same tree walk.

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 666 matching lines @@
     IntRect clippedAbsoluteBoundingBox;
     IntRect unclippedAbsoluteBoundingBox;
     const LayoutObject* clippingContainer;
   };
 
   void setNeedsCompositingInputsUpdate();
   bool childNeedsCompositingInputsUpdate() const {
     return m_childNeedsCompositingInputsUpdate;
   }
   bool needsCompositingInputsUpdate() const {
-    // While we're updating the compositing inputs, these values may differ.
-    // We should never be asking for this value when that is the case.
-    DCHECK(m_needsDescendantDependentCompositingInputsUpdate ==
-           m_needsAncestorDependentCompositingInputsUpdate);
-    return m_needsDescendantDependentCompositingInputsUpdate;
+    return m_needsAncestorDependentCompositingInputsUpdate;
   }
 
   void updateAncestorOverflowLayer(const PaintLayer* ancestorOverflowLayer) {
     m_ancestorOverflowLayer = ancestorOverflowLayer;
   }
   void updateAncestorDependentCompositingInputs(
       const AncestorDependentCompositingInputs&,
       bool hasAncestorWithClipPath);
   void updateDescendantDependentCompositingInputs(
       bool hasDescendantWithClipPath,
@@ skipping 56 matching lines @@
     DCHECK(!m_needsAncestorDependentCompositingInputsUpdate);
     return m_ancestorDependentCompositingInputs
                ? m_ancestorDependentCompositingInputs->clipParent
                : nullptr;
   }
   bool hasAncestorWithClipPath() const {
     DCHECK(!m_needsAncestorDependentCompositingInputsUpdate);
     return m_hasAncestorWithClipPath;
   }
   bool hasDescendantWithClipPath() const {
-    DCHECK(!m_needsDescendantDependentCompositingInputsUpdate);
+    DCHECK(!m_needsDescendantDependentFlagsUpdate);
     return m_hasDescendantWithClipPath;
   }
+
+  // Returns true if there is a descendant with blend-mode that is
+  // not contained within another enclosing stacking context other
+  // than the stacking context blend-mode creates, or the stacking
+  // context this PaintLayer might create. This is needed because
+  // blend-mode content needs to blend with the containing stacking
+  // context's painted output, but not the content in any grandparent
+  // stacking contexts.
   bool hasNonIsolatedDescendantWithBlendMode() const;
 
   bool hasRootScrollerAsDescendant() const {
-    DCHECK(!m_needsDescendantDependentCompositingInputsUpdate);
+    DCHECK(!m_needsDescendantDependentFlagsUpdate);
     return m_hasRootScrollerAsDescendant;
   }
 
   bool lostGroupedMapping() const {
     DCHECK(isAllowedToQueryCompositingState());
     return m_lostGroupedMapping;
   }
   void setLostGroupedMapping(bool b) { m_lostGroupedMapping = b; }
 
   CompositingReasons getCompositingReasons() const {
@@ skipping 184 matching lines @@
   bool has3DTransformedDescendant() const {
     DCHECK(!m_is3DTransformedDescendantDirty);
     return m_has3DTransformedDescendant;
   }
 
 #if CHECK_DISPLAY_ITEM_CLIENT_ALIVENESS
   void endShouldKeepAliveAllClientsRecursive();
 #endif
 
  private:
+  void setNeedsCompositingInputsUpdateInternal();
+
   // Bounding box in the coordinates of this layer.
   LayoutRect logicalBoundingBox() const;
 
   bool hasOverflowControls() const;
 
   void dirtyAncestorChainHasSelfPaintingLayerDescendantStatus();
 
   void updateLayerPositionRecursive();
   void updateLayerPositionsAfterScrollRecursive(
       const DoubleSize& scrollDelta,
@@ skipping 148 matching lines @@
 #endif
 
   unsigned m_is3DTransformedDescendantDirty : 1;
   // Set on a stacking context layer that has 3D descendants anywhere
   // in a preserves3D hierarchy. Hint to do 3D-aware hit testing.
   unsigned m_has3DTransformedDescendant : 1;
 
   unsigned m_containsDirtyOverlayScrollbars : 1;
 
   unsigned m_needsAncestorDependentCompositingInputsUpdate : 1;
-  unsigned m_needsDescendantDependentCompositingInputsUpdate : 1;
   unsigned m_childNeedsCompositingInputsUpdate : 1;
 
   // Used only while determining what layers should be composited. Applies to
   // the tree of z-order lists.
   unsigned m_hasCompositingDescendant : 1;
 
   // True iff we have scrollable overflow and all children of m_layoutObject are
   // known to paint exclusively into their own composited layers.  Set by
   // updateScrollingStateAfterCompositingChange().
   unsigned m_isAllScrollingContentComposited : 1;
@@ skipping 68 matching lines @@
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 CORE_EXPORT void showLayerTree(const blink::PaintLayer*);
 CORE_EXPORT void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif  // Layer_h