Reland of "Move UndoStack from Page to Editor"

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

 /*
  * Copyright (C) 2006, 2007, 2008 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 235 matching lines @@
     private:
         Member<Editor> m_editor;
     };
     friend class RevealSelectionScope;
 
     DECLARE_TRACE();
 
 private:
     Member<LocalFrame> m_frame;
     Member<CompositeEditCommand> m_lastEditCommand;
+    const Member<UndoStack> m_undoStack;
     int m_preventRevealSelection;
     bool m_shouldStartNewKillRingSequence;
     bool m_shouldStyleWithCSS;
     const std::unique_ptr<KillRing> m_killRing;
     VisibleSelection m_mark;
     bool m_areMarkedTextMatchesHighlighted;
     EditorParagraphSeparator m_defaultParagraphSeparator;
     bool m_overwriteModeEnabled;
 
     explicit Editor(LocalFrame&);
 
     LocalFrame& frame() const
     {
         DCHECK(m_frame);
         return *m_frame;
     }
 
     bool canDeleteRange(const EphemeralRange&) const;
     bool shouldDeleteRange(const EphemeralRange&) const;
 
-    UndoStack* undoStack() const;
-
     bool tryDHTMLCopy();
     bool tryDHTMLCut();
     bool tryDHTMLPaste(PasteMode);
 
     bool canSmartReplaceWithPasteboard(Pasteboard*);
     void pasteAsPlainTextWithPasteboard(Pasteboard*);
     void pasteWithPasteboard(Pasteboard*);
     void writeSelectionToPasteboard();
     bool dispatchCPPEvent(const AtomicString&, DataTransferAccessPolicy, PasteMode = AllMimeTypes);
 
@@ skipping 26 matching lines @@
 
 inline bool Editor::markedTextMatchesAreHighlighted() const
 {
     return m_areMarkedTextMatchesHighlighted;
 }
 
 
 } // namespace blink
 
 #endif // Editor_h