Ignoring the timezone policy if it is set to an empty string.

chrome/browser/policy/browser_policy_connector.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/policy/browser_policy_connector.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
@@ skipping 456 matching lines @@
   typedef chromeos::CrosSettingsProvider Provider;
   Provider::TrustedStatus result =
       chromeos::CrosSettings::Get()->PrepareTrustedValues(
           base::Bind(&BrowserPolicyConnector::SetTimezoneIfPolicyAvailable,
                      weak_ptr_factory_.GetWeakPtr()));
 
   if (result != Provider::TRUSTED)
     return;
 
   std::string timezone;
-  if (chromeos::CrosSettings::Get()->GetString(
-          chromeos::kSystemTimezonePolicy, &timezone)) {
+  if (chromeos::CrosSettings::Get()->GetString(chromeos::kSystemTimezonePolicy,
+                                               &timezone) &&
+      !timezone.empty()) {
     chromeos::system::TimezoneSettings::GetInstance()->SetTimezoneFromID(
         UTF8ToUTF16(timezone));
   }
 #endif
 }
 
 scoped_ptr<PolicyService>
     BrowserPolicyConnector::CreatePolicyServiceWithProviders(
         ConfigurationPolicyProvider* user_cloud_policy_provider,
         ConfigurationPolicyProvider* managed_mode_policy_provider) {
@@ skipping 42 matching lines @@
     return new AsyncPolicyProvider(loader.Pass());
   } else {
     return NULL;
   }
 #else
   return NULL;
 #endif
 }
 
 }  // namespace policy