Fix potential crashes in NetworkHandler code

chromeos/network/client_cert_resolver.h

 // Copyright 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_CLIENT_CERT_RESOLVER_H_
 #define CHROMEOS_NETWORK_CLIENT_CERT_RESOLVER_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 104 matching lines @@
   void ConfigureCertificates(std::vector<NetworkAndMatchingCert>* matches);
 
   // Trigger a ResolveRequestCompleted event on all observers.
   void NotifyResolveRequestCompleted();
 
   // Returns Time::Now() unless a mock clock has been installed with
   // SetClockForTesting, in which case the time according to that clock is used
   // instead.
   base::Time Now() const;
 
-  base::ObserverList<Observer> observers_;
+  base::ObserverList<Observer, true> observers_;
 
   // The set of networks that were checked/resolved in previous passes. These
   // networks are skipped in the NetworkListChanged notification.
   std::set<std::string> resolved_networks_;
 
   // The list of network paths that still have to be resolved.
   std::set<std::string> queued_networks_to_resolve_;
 
   // True if currently a resolve task is running.
   bool resolve_task_running_;
@@ skipping 15 matching lines @@
   base::Clock* testing_clock_;
 
   base::WeakPtrFactory<ClientCertResolver> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientCertResolver);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_NETWORK_CLIENT_CERT_RESOLVER_H_