Add mac-only "Set Up Automatic Updates..." button to the new about page.

chrome/browser/ui/webui/help/version_updater.h

 // Copyright (c) 2012 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_UI_WEBUI_HELP_VERSION_UPDATER_H_
 #define CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 21 matching lines @@
     FAILED_OFFLINE,
     FAILED_CONNECTION_TYPE_DISALLOWED,
     DISABLED,
     DISABLED_BY_ADMIN
   };
 
   // Promotion state (Mac-only).
   enum PromotionState {
     PROMOTE_HIDDEN,
     PROMOTE_ENABLED,
-    PROMOTE_DISABLED
+    PROMOTE_DISABLED,
+    PROMOTED,
   };
 
   // TODO(jhawkins): Use a delegate interface instead of multiple callback
   // types.
 #if defined(OS_CHROMEOS)
   typedef base::Callback<void(const std::string&)> ChannelCallback;
   typedef base::Callback<void(update_engine::EndOfLifeStatus status)>
       EolStatusCallback;
 #endif
 
@@ skipping 29 matching lines @@
 #if defined(OS_CHROMEOS)
   virtual void SetChannel(const std::string& channel,
                           bool is_powerwash_allowed) = 0;
   virtual void GetChannel(bool get_current_channel,
                           const ChannelCallback& callback) = 0;
   virtual void GetEolStatus(const EolStatusCallback& callback) = 0;
 #endif
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_H_