Fix GraphicsLayerUpdater::UpdateContext::compositingContainer() for corner cases

third_party/WebKit/Source/core/layout/compositing/GraphicsLayerUpdater.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 36 matching lines @@
     CompositingState compositingState = layer.compositingState();
     if (compositingState != NotComposited &&
         compositingState != PaintsIntoGroupedBacking) {
       m_compositingAncestor = &layer;
       if (layer.stackingNode()->isStackingContext())
         m_compositingStackingContext = &layer;
     }
   }
 
   const PaintLayer* compositingContainer(const PaintLayer& layer) const {
-    if (layer.stackingNode()->isStacked())
-      return m_compositingStackingContext;
+    const PaintLayer* compositingContainer;
+    if (layer.stackingNode()->isStacked()) {
+      compositingContainer = m_compositingStackingContext;
+    } else if ((layer.parent() &&
+                !layer.parent()->layoutObject().isLayoutBlock()) ||
+               layer.layoutObject().isColumnSpanAll()) {
+      // In these cases, compositingContainer may escape the normal layer
+      // hierarchy. Use the slow path to ensure correct result.
+      // See PaintLayer::containingLayer() for details.
+      compositingContainer =
+          layer.enclosingLayerWithCompositedLayerMapping(ExcludeSelf);
+    } else {
+      compositingContainer = m_compositingAncestor;
+    }
 
-    // TODO(wangxianzhu, chrishtr): This is incorrect if m_compositingAncestor
-    // is inline and there is any non-layer floating object between layer and
-    // m_compositingAncestor. Should use the logic in PaintLayer::
-    // containingLayer().
-    if (layer.layoutObject().isFloatingWithNonContainingBlockParent())
-      return layer.enclosingLayerWithCompositedLayerMapping(ExcludeSelf);
-
-    return m_compositingAncestor;
+    // We should always get the same result as the slow path.
+    DCHECK_EQ(compositingContainer,
+              layer.enclosingLayerWithCompositedLayerMapping(ExcludeSelf));
+    return compositingContainer;
   }
 
   const PaintLayer* compositingStackingContext() const {
     return m_compositingStackingContext;
   }
 
  private:
   const PaintLayer* m_compositingStackingContext;
   const PaintLayer* m_compositingAncestor;
 };
@@ skipping 13 matching lines @@
 
 void GraphicsLayerUpdater::updateRecursive(
     PaintLayer& layer,
     UpdateType updateType,
     const UpdateContext& context,
     Vector<PaintLayer*>& layersNeedingPaintInvalidation) {
   if (layer.hasCompositedLayerMapping()) {
     CompositedLayerMapping* mapping = layer.compositedLayerMapping();
 
     if (updateType == ForceUpdate || mapping->needsGraphicsLayerUpdate()) {
-      const PaintLayer* compositingContainer =
-          context.compositingContainer(layer);
-      DCHECK_EQ(compositingContainer,
-                layer.enclosingLayerWithCompositedLayerMapping(ExcludeSelf));
-
       if (mapping->updateGraphicsLayerConfiguration())
         m_needsRebuildTree = true;
-
-      mapping->updateGraphicsLayerGeometry(compositingContainer,
+      mapping->updateGraphicsLayerGeometry(context.compositingContainer(layer),
                                            context.compositingStackingContext(),
                                            layersNeedingPaintInvalidation);
       if (PaintLayerScrollableArea* scrollableArea = layer.getScrollableArea())
         scrollableArea->positionOverflowControls();
       updateType = mapping->updateTypeForChildren(updateType);
       mapping->clearNeedsGraphicsLayerUpdate();
     }
   }
 
   UpdateContext childContext(context, layer);
@@ skipping 12 matching lines @@
         ->assertNeedsToUpdateGraphicsLayerBitsCleared();
 
   for (PaintLayer* child = layer.firstChild(); child;
        child = child->nextSibling())
     assertNeedsToUpdateGraphicsLayerBitsCleared(*child);
 }
 
 #endif
 
 }  // namespace blink