Fix potential crashes in NetworkHandler code

chromeos/network/network_profile_handler.h

 // 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.
 
 #ifndef CHROMEOS_NETWORK_NETWORK_PROFILE_HANDLER_H_
 #define CHROMEOS_NETWORK_NETWORK_PROFILE_HANDLER_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 63 matching lines @@
   void AddProfile(const NetworkProfile& profile);
   void RemoveProfile(const std::string& profile_path);
 
  private:
   ProfileList profiles_;
 
   // Contains the profile paths for which properties were requested. Once the
   // properties are retrieved and the path is still in this set, a new profile
   // object is created.
   std::set<std::string> pending_profile_creations_;
-  base::ObserverList<NetworkProfileObserver> observers_;
+  base::ObserverList<NetworkProfileObserver, true> observers_;
 
   // For Shill client callbacks
   base::WeakPtrFactory<NetworkProfileHandler> weak_ptr_factory_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NetworkProfileHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_NETWORK_NETWORK_PROFILE_HANDLER_H_