[Mac] Implement the update available notification in the wrench menu.

chrome/browser/wrench_menu_model.cc

 // 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.
 
 #include "chrome/browser/wrench_menu_model.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "app/l10n_util.h"
@@ skipping 237 matching lines @@
   AddItemWithStringId(IDC_SHOW_HISTORY, IDS_SHOW_HISTORY);
   AddItemWithStringId(IDC_SHOW_DOWNLOADS, IDS_SHOW_DOWNLOADS);
   AddSeparator();
 
 #if defined(OS_MACOSX)
   AddItemWithStringId(IDC_OPTIONS, IDS_PREFERENCES_MAC);
 #else
   AddItemWithStringId(IDC_OPTIONS, IDS_OPTIONS);
 #endif
 
-  if (browser_defaults::kShowAboutMenuItem) {
+  // On Mac, there is no About item unless it is replaced with the update
+  // available notification.
+  if (browser_defaults::kShowAboutMenuItem ||
+      Singleton<UpgradeDetector>::get()->notify_upgrade()) {
     AddItem(IDC_ABOUT,
             l10n_util::GetStringFUTF16(
                 IDS_ABOUT,
                 l10n_util::GetStringUTF16(IDS_PRODUCT_NAME)));
   }
   AddItemWithStringId(IDC_HELP_PAGE, IDS_HELP_PAGE);
   if (browser_defaults::kShowExitMenuItem) {
     AddSeparator();
 #if defined(OS_CHROMEOS)
     AddItemWithStringId(IDC_EXIT, IDS_SIGN_OUT);
@@ skipping 59 matching lines @@
   }
   return l10n_util::GetStringFUTF16(
       IDS_ABOUT, l10n_util::GetStringUTF16(IDS_PRODUCT_NAME));
 }
 
 bool WrenchMenuModel::IsDynamicItem(int index) const {
   int command_id = GetCommandIdAt(index);
   return command_id == IDC_SYNC_BOOKMARKS ||
          command_id == IDC_ABOUT;
 }