BookmarkClient can add extra nodes to BookmarkModel.

components/bookmarks/browser/bookmark_model.h

 // Copyright 2014 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 COMPONENTS_BOOKMARKS_BROWSER_BOOKMARK_MODEL_H_
 #define COMPONENTS_BOOKMARKS_BROWSER_BOOKMARK_MODEL_H_
 
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 80 matching lines @@
 
   // Returns the 'other' node. This is NULL until loaded.
   const BookmarkNode* other_node() const { return other_node_; }
 
   // Returns the 'mobile' node. This is NULL until loaded.
   const BookmarkNode* mobile_node() const { return mobile_node_; }
 
   bool is_root_node(const BookmarkNode* node) const { return node == &root_; }
 
   // Returns whether the given |node| is one of the permanent nodes - root node,
-  // 'bookmark bar' node, 'other' node or 'mobile' node.
+  // 'bookmark bar' node, 'other' node or 'mobile' node, or one of the root
+  // nodes supplied by the |client_|.
   bool is_permanent_node(const BookmarkNode* node) const {
-    return node == &root_ ||
-           node == bookmark_bar_node_ ||
-           node == other_node_ ||
-           node == mobile_node_;
+    return node && (node == &root_ || node->parent() == &root_);
   }
 
   // Returns the parent the last node was added to. This never returns NULL
   // (as long as the model is loaded).
   const BookmarkNode* GetParentForNewNodes();
 
   void AddObserver(BookmarkModelObserver* observer);
   void RemoveObserver(BookmarkModelObserver* observer);
 
   // Notifies the observers that an extensive set of changes is about to happen,
@@ skipping 302 matching lines @@
 
   // See description of IsDoingExtensiveChanges above.
   int extensive_changes_;
 
   scoped_ptr<BookmarkExpandedStateTracker> expanded_state_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(BookmarkModel);
 };
 
 #endif  // COMPONENTS_BOOKMARKS_BROWSER_BOOKMARK_MODEL_H_