Fix potential crashes in NetworkHandler code

chromeos/network/auto_connect_handler.cc

 // Copyright 2014 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/auto_connect_handler.h"
 
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/location.h"
@@ skipping 19 matching lines @@
       request_best_connection_pending_(false),
       device_policy_applied_(false),
       user_policy_applied_(false),
       client_certs_resolved_(false),
       applied_autoconnect_policy_(false),
       connect_to_best_services_after_scan_(false),
       weak_ptr_factory_(this) {
 }
 
 AutoConnectHandler::~AutoConnectHandler() {
+  if (LoginState::IsInitialized())
+    LoginState::Get()->RemoveObserver(this);
   if (client_cert_resolver_)
     client_cert_resolver_->RemoveObserver(this);
-  if (LoginState::IsInitialized())
-    LoginState::Get()->RemoveObserver(this);
+  if (network_connection_handler_)
+    network_connection_handler_->RemoveObserver(this);
   if (network_state_handler_)
     network_state_handler_->RemoveObserver(this, FROM_HERE);
   if (managed_configuration_handler_)
     managed_configuration_handler_->RemoveObserver(this);
 }
 
 void AutoConnectHandler::Init(
     ClientCertResolver* client_cert_resolver,
     NetworkConnectionHandler* network_connection_handler,
     NetworkStateHandler* network_state_handler,
@@ skipping 201 matching lines @@
 void AutoConnectHandler::CallShillConnectToBestServices() const {
   NET_LOG_EVENT("ConnectToBestServices", "");
   DBusThreadManager::Get()->GetShillManagerClient()->ConnectToBestServices(
       base::Bind(&base::DoNothing),
       base::Bind(&network_handler::ShillErrorCallbackFunction,
                  "ConnectToBestServices Failed",
                  "", network_handler::ErrorCallback()));
 }
 
 }  // namespace chromeos