Make sure that ServiceWorkerContainer::m_navigator is not null

third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerContainer.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 120 matching lines @@
 
 ServiceWorkerContainer::~ServiceWorkerContainer() {
   ASSERT(!m_provider);
 }
 
 void ServiceWorkerContainer::contextDestroyed() {
   if (m_provider) {
     m_provider->setClient(0);
     m_provider = nullptr;
   }
-  if (m_navigator)
-    m_navigator->clearServiceWorker();
+  m_navigator->clearServiceWorker();
 }
 
 DEFINE_TRACE(ServiceWorkerContainer) {
   visitor->trace(m_controller);
   visitor->trace(m_ready);
   visitor->trace(m_navigator);
   EventTargetWithInlineData::trace(visitor);
   ContextLifecycleObserver::trace(visitor);
 }
 
@@ skipping 321 matching lines @@
 
   if (ServiceWorkerContainerClient* client =
           ServiceWorkerContainerClient::from(executionContext)) {
     m_provider = client->provider();
     if (m_provider)
       m_provider->setClient(this);
   }
 }
 
 }  // namespace blink