ChromeOS: Add SystemTimezoneAutomaticDetection policy.

chrome/browser/chromeos/system/timezone_resolver_manager.h

 // Copyright 2016 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_CHROMEOS_SYSTEM_TIMEZONE_RESOLVER_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_SYSTEM_TIMEZONE_RESOLVER_MANAGER_H_
 
 #include "base/macros.h"
 #include "chromeos/timezone/timezone_resolver.h"
 #include "components/prefs/pref_change_registrar.h"
@@ skipping 22 matching lines @@
   bool ShouldApplyResolvedTimezone();
 
  private:
   // Returns true if TimeZoneResolver should be running and taking in account
   // all configuration data.
   bool IsTimeZoneResolverShouldBeRunnig();
 
   // This is non-null only after user logs in.
   PrefService* primary_user_prefs_;
 
+  // This is used to subscribe to policy preference.
+  PrefChangeRegistrar local_state_pref_change_registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(TimeZoneResolverManager);
 };
 
 }  // namespace system
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_SYSTEM_TIMEZONE_RESOLVER_MANAGER_H_