Clean compositing inputs for location APIs for sticky-affected elements.

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 166 matching lines @@
 
   bool HasSelfPaintingLayer() const;
   PaintLayer* Layer() const {
     return GetRarePaintData() ? GetRarePaintData()->Layer() : nullptr;
   }
   // The type of PaintLayer to instantiate. Any value returned from this
   // function other than NoPaintLayer will lead to a PaintLayer being created.
   virtual PaintLayerType LayerTypeRequired() const = 0;
   PaintLayerScrollableArea* GetScrollableArea() const;
 
+  bool IsInStickySubtree() const { return is_in_sticky_subtree_; }
+
   virtual void UpdateFromStyle();
 
   // This will work on inlines to return the bounding box of all of the lines'
   // border boxes.
   virtual IntRect BorderBoundingBox() const = 0;
 
   virtual LayoutRect VisualOverflowRect() const = 0;
 
   // Checks if this box, or any of it's descendants, or any of it's
   // continuations, will take up space in the layout of the page.
@@ skipping 342 matching lines @@
   LayoutUnit ComputedCSSPadding(const Length&) const;
   bool IsBoxModelObject() const final { return true; }
 
   LayoutBoxModelObjectRareData& EnsureRareData() {
     if (!rare_data_)
       rare_data_ = WTF::MakeUnique<LayoutBoxModelObjectRareData>();
     return *rare_data_.get();
   }
 
   std::unique_ptr<LayoutBoxModelObjectRareData> rare_data_;
+
+  bool is_in_sticky_subtree_;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBoxModelObject, IsBoxModelObject());
 
 }  // namespace blink
 
 #endif  // LayoutBoxModelObject_h