Attempt at fixing crash. I believe this is happening during session...

chrome/browser/bookmark_bar_model.h

 // Copyright (c) 2006-2008 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_BOOKMARK_BAR_MODEL_H_
 #define CHROME_BROWSER_BOOKMARK_BAR_MODEL_H_
 
 #include "base/lock.h"
 #include "base/observer_list.h"
 #include "base/scoped_handle.h"
@@ skipping 110 matching lines @@
 
 // BookmarkBarModelObserver ---------------------------------------------------
 
 // Observer for the BookmarkBarModel.
 //
 class BookmarkBarModelObserver {
  public:
   // Invoked when the model has finished loading.
   virtual void Loaded(BookmarkBarModel* model) = 0;
 
+  // Invoked from the destructor of the BookmarkBarModel.
+  virtual void BookmarkModelBeingDeleted(BookmarkBarModel* model) { }
+
   // Invoked when a node has moved.
   virtual void BookmarkNodeMoved(BookmarkBarModel* model,
                                  BookmarkBarNode* old_parent,
                                  int old_index,
                                  BookmarkBarNode* new_parent,
                                  int new_index) = 0;
 
   // Invoked when a node has been added.
   virtual void BookmarkNodeAdded(BookmarkBarModel* model,
                                  BookmarkBarNode* parent,
@@ skipping 283 matching lines @@
   bool waiting_for_history_load_;
 
   // Handle to event signaled when loading is done.
   ScopedHandle loaded_signal_;
 
   DISALLOW_EVIL_CONSTRUCTORS(BookmarkBarModel);
 };
 
 #endif  // CHROME_BROWSER_BOOKMARK_BAR_MODEL_H_