Land layer squashing behind a flag

Source/core/rendering/RenderLayer.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 336 matching lines @@
 
     CompositedLayerMappingPtr compositedLayerMapping() const { return m_compositedLayerMapping.get(); }
     CompositedLayerMappingPtr ensureCompositedLayerMapping();
 
     // NOTE: If you are using hasCompositedLayerMapping to determine the state of compositing for this layer,
     // (and not just to do bookkeeping related to the mapping like, say, allocating or deallocating a mapping),
     // then you may have incorrect logic. Use compositingState() instead.
     bool hasCompositedLayerMapping() const { return m_compositedLayerMapping.get(); }
     void clearCompositedLayerMapping(bool layerBeingDestroyed = false);
 
+    CompositedLayerMapping* groupedMapping() const { return m_groupedMapping; }
+    void setGroupedMapping(CompositedLayerMapping* groupedMapping) { m_groupedMapping = groupedMapping; }
+
     bool hasCompositedMask() const;
     bool hasCompositedClippingMask() const;
     bool needsCompositedScrolling() const { return m_scrollableArea && m_scrollableArea->needsCompositedScrolling(); }
 
     RenderLayer* scrollParent() const;
     RenderLayer* clipParent() const;
 
     bool needsCompositingLayersRebuiltForClip(const RenderStyle* oldStyle, const RenderStyle* newStyle) const;
     bool needsCompositingLayersRebuiltForOverflow(const RenderStyle* oldStyle, const RenderStyle* newStyle) const;
     bool needsCompositingLayersRebuiltForFilters(const RenderStyle* oldStyle, const RenderStyle* newStyle, bool didPaintWithFilters) const;
@@ skipping 70 matching lines @@
         // RenderObject::canContainFixedPositionedObject() should probably be used
         // instead.
         RenderLayerModelObject* layerRenderer = renderer();
         return isRootLayer() || layerRenderer->isPositioned() || hasTransform();
     }
 
     void paintLayer(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
 
     PassOwnPtr<Vector<FloatRect> > collectTrackedRepaintRects() const;
 
+    void setOffsetFromSquashingLayerOrigin(IntSize offset) { m_compositingProperties.offsetFromSquashingLayerOrigin = offset; }
+    IntSize offsetFromSquashingLayerOrigin() const { return m_compositingProperties.offsetFromSquashingLayerOrigin; }
+
 private:
     bool hasOverflowControls() const;
 
     void setIsUnclippedDescendant(bool isUnclippedDescendant) { m_isUnclippedDescendant = isUnclippedDescendant; }
 
     void setAncestorChainHasSelfPaintingLayerDescendant();
     void dirtyAncestorChainHasSelfPaintingLayerDescendantStatus();
 
     void setAncestorChainHasOutOfFlowPositionedDescendant();
     void dirtyAncestorChainHasOutOfFlowPositionedDescendantStatus();
@@ skipping 253 matching lines @@
         bool hasNonCompositedChild : 1;
 
         // Should be for stacking contexts having unisolated blending descendants.
         bool shouldIsolateCompositedDescendants : 1;
 
         // The reason, if any exists, that a fixed-position layer is chosen not to be composited.
         unsigned viewportConstrainedNotCompositedReason : 2;
 
         // Once computed, indicates all that a layer needs to become composited using the CompositingReasons enum bitfield.
         CompositingReasons compositingReasons;
+
+        // Used for invalidating this layer's contents on the squashing GraphicsLayer.
+        IntSize offsetFromSquashingLayerOrigin;
     };
 
     CompositingProperties m_compositingProperties;
 
 private:
     enum CompositedScrollingHistogramBuckets {
         IsScrollableAreaBucket = 0,
         NeedsToBeStackingContainerBucket = 1,
         WillUseCompositedScrollingBucket = 2,
         CompositedScrollingHistogramMax = 3
     };
 
     IntRect m_blockSelectionGapsBounds;
 
     OwnPtr<CompositedLayerMapping> m_compositedLayerMapping;
     OwnPtr<RenderLayerScrollableArea> m_scrollableArea;
 
+    CompositedLayerMapping* m_groupedMapping;
+
     RenderLayerRepainter m_repainter;
     RenderLayerClipper m_clipper; // FIXME: Lazily allocate?
     OwnPtr<RenderLayerStackingNode> m_stackingNode;
     OwnPtr<RenderLayerReflectionInfo> m_reflectionInfo;
 };
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h