Update NetworkStateNotifier to use message_center.

ash/system/chromeos/network/network_observer.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 "ash/system/chromeos/network/network_observer.h"
-
-#include "chromeos/network/network_state.h"
-#include "third_party/cros_system_api/dbus/service_constants.h"
-
-namespace ash {
-
-//static
-NetworkObserver::NetworkType NetworkObserver::GetNetworkTypeForNetworkState(
-    const chromeos::NetworkState* network) {
-  if (!network)
-    return NETWORK_UNKNOWN;
-  const std::string& type = network->type();
-  if (type == flimflam::kTypeCellular) {
-    const std::string& technology = network->network_technology();
-    if (technology == flimflam::kNetworkTechnologyLte ||
-        technology == flimflam::kNetworkTechnologyLteAdvanced)
-      return NETWORK_CELLULAR_LTE;
-    else
-      return NETWORK_CELLULAR;
-  }
-  if (type == flimflam::kTypeEthernet)
-     return NETWORK_ETHERNET;
-  if (type == flimflam::kTypeWifi)
-     return NETWORK_WIFI;
-  if (type == flimflam::kTypeBluetooth)
-     return NETWORK_BLUETOOTH;
-  return NETWORK_UNKNOWN;
-}
-
-}  // namespace ash