Fix potential crashes in NetworkHandler code

chromeos/network/network_sms_handler.h

 // 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.
 
 #ifndef CHROMEOS_NETWORK_NETWORK_SMS_HANDLER_H_
 #define CHROMEOS_NETWORK_NETWORK_SMS_HANDLER_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 72 matching lines @@
 
   // Requests properties for each entry in |devices|.
   void UpdateDevices(const base::ListValue* devices);
 
   // Callback to handle the device properties for |device_path|.
   // A NetworkSmsDeviceHandler will be instantiated for each cellular device.
   void DevicePropertiesCallback(const std::string& device_path,
                                 DBusMethodCallStatus call_status,
                                 const base::DictionaryValue& properties);
 
-  base::ObserverList<Observer> observers_;
+  base::ObserverList<Observer, true> observers_;
   ScopedVector<NetworkSmsDeviceHandler> device_handlers_;
   ScopedVector<base::DictionaryValue> received_messages_;
   base::WeakPtrFactory<NetworkSmsHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkSmsHandler);
 };
 
-}  // namespace
+}  // namespace chromeos
 
 #endif  // CHROMEOS_NETWORK_NETWORK_SMS_HANDLER_H_