Bookmark Undo service for multiple level undo/redo of bookmarks.

chrome/browser/undo/bookmark_renumber_observer.h

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UNDO_BOOKMARK_RENUMBER_OBSERVER_H_
+#define CHROME_BROWSER_UNDO_BOOKMARK_RENUMBER_OBSERVER_H_
+
+class BookmarkRenumberObserver {
+ public:
+  // Invoked when a bookmark id has been renumbered so that any
+  // BookmarkUndoOperations that refer to that bookmark can be updated.
+  virtual void OnBookmarkRenumbered(int64 old_id, int64 new_id) = 0;
+
+ protected:
+  virtual ~BookmarkRenumberObserver() {}
+};
+
+#endif  // CHROME_BROWSER_UNDO_BOOKMARK_RENUMBER_OBSERVER_H_