Selection API: extend() should operate DOM Ranges.

third_party/WebKit/Source/core/editing/DOMSelection.h

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2012 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.
@@ skipping 93 matching lines @@
   DECLARE_VIRTUAL_TRACE();
 
  private:
   explicit DOMSelection(const TreeScope*);
 
   bool isAvailable() const;
 
   // Convenience methods for accessors, does not check m_frame present.
   const VisibleSelection& visibleSelection() const;
   bool isBaseFirstInSelection() const;
+  const Position& anchorPosition() const;
 
   Node* shadowAdjustedNode(const Position&) const;
   int shadowAdjustedOffset(const Position&) const;
 
   bool isValidForPosition(Node*) const;
 
   void addConsoleError(const String& message);
   Range* primaryRangeOrNull() const;
   Range* createRangeFromSelectionEditor() const;
 
   bool isSelectionOfDocument() const;
   void cacheRangeIfSelectionOfDocument(Range*) const;
   Range* documentCachedRange() const;
   void clearCachedRangeIfSelectionOfDocument();
 
   Member<const TreeScope> m_treeScope;
 };
 
 }  // namespace blink
 
 #endif  // DOMSelection_h