Add support to Google Update wrappers for the "automatic updates only" group policy setting.

chrome/installer/util/google_update_settings.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_INSTALLER_UTIL_GOOGLE_UPDATE_SETTINGS_H_
 #define CHROME_INSTALLER_UTIL_GOOGLE_UPDATE_SETTINGS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 12 matching lines @@
 // This class provides accessors to the Google Update 'ClientState' information
 // that recorded when the user downloads the chrome installer. It is
 // google_update.exe responsibility to write the initial values.
 class GoogleUpdateSettings {
  public:
   // Update policy constants defined by Google Update; do not change these.
   enum UpdatePolicy {
     UPDATES_DISABLED    = 0,
     AUTOMATIC_UPDATES   = 1,
     MANUAL_UPDATES_ONLY = 2,
+    AUTO_UPDATES_ONLY   = 3,
   };
 
   // Defines product data that is tracked/used by Google Update.
   struct ProductData {
     // The currently installed version.
     std::string version;
     // The time that Google Update last updated this product.  (This means
     // either running an updater successfully, or doing an update check that
     // results in no update available.)
     base::Time last_success;
@@ skipping 227 matching lines @@
   // this will do nothing to |experiment_labels|. This will return true if the
   // label did not exist, or was successfully read.
   static bool ReadExperimentLabels(bool system_install,
                                    string16* experiment_labels);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(GoogleUpdateSettings);
 };
 
 #endif  // CHROME_INSTALLER_UTIL_GOOGLE_UPDATE_SETTINGS_H_