Implement position: sticky updates on compositor

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h

 /*
  * Copyright (C) 2009, 2010, 2011 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 174 matching lines @@
     bool needsToReparentOverflowControls() const;
 
     // Removes the overflow controls host layer from its parent and positions it
     // so that it can be inserted as a sibling to this CLM without changing
     // position.
     GraphicsLayer* detachLayerForOverflowControls(const PaintLayer& enclosingLayer);
 
     void updateFilters(const ComputedStyle&);
     void updateBackdropFilters(const ComputedStyle&);
 
+    void updateStickyConstraints(const ComputedStyle&);
+
     void setBlendMode(WebBlendMode);
 
     bool needsGraphicsLayerUpdate() { return m_pendingUpdateScope > GraphicsLayerUpdateNone; }
     void setNeedsGraphicsLayerUpdate(GraphicsLayerUpdateScope scope) { m_pendingUpdateScope = std::max(static_cast<GraphicsLayerUpdateScope>(m_pendingUpdateScope), scope); }
     void clearNeedsGraphicsLayerUpdate() { m_pendingUpdateScope = GraphicsLayerUpdateNone; }
 
     GraphicsLayerUpdater::UpdateType updateTypeForChildren(GraphicsLayerUpdater::UpdateType) const;
 
 #if ENABLE(ASSERT)
     void assertNeedsToUpdateGraphicsLayerBitsCleared() {  ASSERT(m_pendingUpdateScope == GraphicsLayerUpdateNone); }
@@ skipping 261 matching lines @@
 
     // Keep track of whether the background is painted onto the scrolling contents layer for invalidations.
     unsigned m_backgroundPaintsOntoScrollingContentsLayer : 1;
 
     friend class CompositedLayerMappingTest;
 };
 
 } // namespace blink
 
 #endif // CompositedLayerMapping_h