Fix debug crash caused by NetworkChangeNotifierChromeos.

net/base/network_change_notifier.cc

 // Copyright (c) 2010 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 "net/base/network_change_notifier.h"
 #include "build/build_config.h"
 #if defined(OS_WIN)
 #include "net/base/network_change_notifier_win.h"
 #elif defined(OS_LINUX)
 #include "net/base/network_change_notifier_linux.h"
@@ skipping 88 matching lines @@
 }
 
 void NetworkChangeNotifier::NotifyObserversOfIPAddressChange() {
   if (g_network_change_notifier) {
     g_network_change_notifier->ip_address_observer_list_->Notify(
         &IPAddressObserver::OnIPAddressChanged);
   }
 }
 
 void NetworkChangeNotifier::NotifyObserversOfOnlineStateChange() {
-  online_state_observer_list_->Notify(
-      &OnlineStateObserver::OnOnlineStateChanged, !IsOffline());
+  if (g_network_change_notifier) {
+    g_network_change_notifier->online_state_observer_list_->Notify(
+        &OnlineStateObserver::OnOnlineStateChanged, !IsOffline());
+  }
 }
 
 }  // namespace net