Adds ability for tree model to reorder its children. I'm going to use...

chrome/views/tree_model.h

 // Copyright (c) 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_VIEWS_TREE_MODEL_H_
 #define CHROME_VIEWS_TREE_MODEL_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 21 matching lines @@
                               TreeModelNode* parent,
                               int start,
                               int count) = 0;
 
   // Notification that nodes were removed from the specified parent.
   virtual void TreeNodesRemoved(TreeModel* model,
                                 TreeModelNode* parent,
                                 int start,
                                 int count) = 0;
 
+  // Notification the children of |parent| have been reordered. Note, only
+  // the direct children of |parent| have been reordered, not descendants.
+  // TODO(sky): make this pure virtual after all sites have been updated.
+  virtual void TreeNodeChildrenReordered(TreeModel* model,
+                                         TreeModelNode* parent) {}
+
   // Notification that the contents of a node has changed.
   virtual void TreeNodeChanged(TreeModel* model, TreeModelNode* node) = 0;
 };
 
 // TreeModel ------------------------------------------------------------------
 
 // The model for TreeView.
 class TreeModel {
  public:
   // Returns the root of the tree. This may or may not be shown in the tree,
@@ skipping 25 matching lines @@
 
   // Returns the index of the icon to use for |node|. Return -1 to use the
   // default icon. The index is relative to the list of icons returned from
   // GetIcons.
   virtual int GetIconIndex(TreeModelNode* node) { return -1; }
 };
 
 }  // namespace views
 
 #endif  // CHROME_VIEWS_TREE_MODEL_H_