Simplify LoginState methods.

chrome/browser/chromeos/settings/system_settings_provider.cc

 // 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.
 
 #include "chrome/browser/chromeos/settings/system_settings_provider.h"
 
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "chromeos/login/login_state.h"
@@ skipping 11 matching lines @@
   timezone_value_.reset(new base::StringValue(
       timezone_settings->GetCurrentTimezoneID()));
 }
 
 SystemSettingsProvider::~SystemSettingsProvider() {
   system::TimezoneSettings::GetInstance()->RemoveObserver(this);
 }
 
 void SystemSettingsProvider::DoSet(const std::string& path,
                                    const base::Value& in_value) {
-  // Non-guest users can change the time zone.
-  if (LoginState::Get()->IsGuestUser())
+  // Only non-guest users can change the time zone.
+  if (LoginState::Get()->IsGuestSessionUser() ||
+      LoginState::Get()->IsPublicSessionUser()) {
     return;
+  }
 
   if (path == kSystemTimezone) {
     base::string16 timezone_id;
     if (!in_value.GetAsString(&timezone_id))
       return;
     // This will call TimezoneChanged.
     system::TimezoneSettings::GetInstance()->SetTimezoneFromID(timezone_id);
   }
 }
 
@@ skipping 14 matching lines @@
 }
 
 void SystemSettingsProvider::TimezoneChanged(const icu::TimeZone& timezone) {
   // Fires system setting change notification.
   timezone_value_.reset(new base::StringValue(
       system::TimezoneSettings::GetTimezoneID(timezone)));
   NotifyObservers(kSystemTimezone);
 }
 
 }  // namespace chromeos