Handle nested position:sticky elements correctly (compositor)

third_party/WebKit/public/platform/WebLayerStickyPositionConstraint.h

 /*
  * Copyright (C) 2013 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 13 matching lines @@
  */
 
 #ifndef WebLayerStickyPositionConstraint_h
 #define WebLayerStickyPositionConstraint_h
 
 #include "public/platform/WebPoint.h"
 #include "public/platform/WebRect.h"
 
 namespace blink {
 
+class WebLayer;
+
 // TODO(flackr): Combine with WebLayerPositionConstraint.
 struct WebLayerStickyPositionConstraint {
   // True if the layer is sticky.
   bool isSticky : 1;
 
   // For each edge, true if the layer should stick to that edge of its
   // ancestor scroller (or the viewport).
   bool isAnchoredLeft : 1;
   bool isAnchoredRight : 1;
   bool isAnchoredTop : 1;
@@ skipping 11 matching lines @@
   WebPoint parentRelativeStickyBoxOffset;
 
   // The layout rectangle of the sticky element before it has been shifted
   // to stick.
   WebRect scrollContainerRelativeStickyBoxRect;
 
   // The layout rectangle of the containing block edges which this sticky
   // element should not be shifted beyond.
   WebRect scrollContainerRelativeContainingBlockRect;
 
+  WebLayer* nearestLayerShiftingStickyBox;
+  WebLayer* nearestLayerShiftingContainingBlock;
+
+  WebFloatSize localStickyOffset;
+
   WebLayerStickyPositionConstraint()
       : isSticky(false),
         isAnchoredLeft(false),
         isAnchoredRight(false),
         isAnchoredTop(false),
         isAnchoredBottom(false),
         leftOffset(0.f),
         rightOffset(0.f),
         topOffset(0.f),
-        bottomOffset(0.f) {}
+        bottomOffset(0.f),
+        nearestLayerShiftingStickyBox(nullptr),
+        nearestLayerShiftingContainingBlock(nullptr) {}
 };
 
 }  // namespace blink
 
 #endif  // WebLayerStickyPositionConstraint_h