The "Update Chrome" menu item should appear in addition to the About menu.

app/menus/menu_model.cc

 // Copyright (c) 2009 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.
 
 #include "app/menus/menu_model.h"
 
 namespace menus {
 
+bool MenuModel::IsVisibleAt(int index) const {
+  return true;
+}
+
 bool MenuModel::GetModelAndIndexForCommandId(int command_id,
                                              MenuModel** model, int* index) {
   int item_count = (*model)->GetItemCount();
   for (int i = 0; i < item_count; ++i) {
     if ((*model)->GetTypeAt(i) == TYPE_SUBMENU) {
       MenuModel* submenu_model = (*model)->GetSubmenuModelAt(i);
       if (GetModelAndIndexForCommandId(command_id, &submenu_model, index)) {
         *model = submenu_model;
         return true;
       }
     }
     if ((*model)->GetCommandIdAt(i) == command_id) {
       *index = i;
       return true;
     }
   }
   return false;
 }
 
 }  // namespace