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

chrome/browser/gtk/menu_gtk.h

 // Copyright (c) 2010 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_GTK_MENU_GTK_H_
 #define CHROME_BROWSER_GTK_MENU_GTK_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 45 matching lines @@
 
   // These methods are used to build the menu dynamically. The return value
   // is the new menu item.
   GtkWidget* AppendMenuItemWithLabel(int command_id, const std::string& label);
   GtkWidget* AppendMenuItemWithIcon(int command_id, const std::string& label,
                                     const SkBitmap& icon);
   GtkWidget* AppendCheckMenuItemWithLabel(int command_id,
                                           const std::string& label);
   GtkWidget* AppendSeparator();
   GtkWidget* AppendMenuItem(int command_id, GtkWidget* menu_item);
-  GtkWidget* AppendMenuItemToMenu(int command_id,
+  GtkWidget* AppendMenuItemToMenu(int index,
+                                  menus::MenuModel* model,
                                   GtkWidget* menu_item,
                                   GtkWidget* menu,
                                   bool connect_to_activate);
 
   // Displays the menu. |timestamp| is the time of activation. The popup is
   // statically positioned at |widget|.
   void Popup(GtkWidget* widget, gint button_type, guint32 timestamp);
 
   // Displays the menu using the button type and timestamp of |event|. The popup
   // is statically positioned at |widget|.
@@ skipping 93 matching lines @@
   // menu.
   static bool block_activation_;
 
   // We must free these at shutdown.
   std::vector<MenuGtk*> submenus_we_own_;
 
   ScopedRunnableMethodFactory<MenuGtk> factory_;
 };
 
 #endif  // CHROME_BROWSER_GTK_MENU_GTK_H_