Use a direct include of strings headers in chromeos/.

chromeos/network/managed_network_configuration_handler.cc

 // Copyright (c) 2013 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 "chromeos/network/managed_network_configuration_handler.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/guid.h"
 #include "base/json/json_writer.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/values.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/shill_manager_client.h"
 #include "chromeos/dbus/shill_profile_client.h"
 #include "chromeos/dbus/shill_service_client.h"
 #include "chromeos/network/network_configuration_handler.h"
 #include "chromeos/network/network_event_log.h"
 #include "chromeos/network/network_handler_callbacks.h"
 #include "chromeos/network/network_profile.h"
@@ skipping 879 matching lines @@
     NetworkStateHandler* network_state_handler,
     NetworkProfileHandler* network_profile_handler,
     NetworkConfigurationHandler* network_configuration_handler) {
   network_state_handler_ = network_state_handler;
   network_profile_handler_ = network_profile_handler;
   network_configuration_handler_ = network_configuration_handler;
   network_profile_handler_->AddObserver(this);
 }
 
 }  // namespace chromeos