Increase the lifetime of Navigation Preload related objects.

third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.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 194 matching lines @@
   DCHECK(fetchEvent);
   fetchEvent->onNavigationPreloadResponse(
       workerGlobalScope()->scriptController()->getScriptState(),
       std::move(response), std::move(dataConsumeHandle));
 }
 
 void ServiceWorkerGlobalScopeProxy::onNavigationPreloadError(
     int fetchEventID,
     std::unique_ptr<WebServiceWorkerError> error) {
   FetchEvent* fetchEvent = m_pendingPreloadFetchEvents.take(fetchEventID);
-  DCHECK(fetchEvent);
+  // This method may be called after onNavigationPreloadResponse() was called.
+  if (!fetchEvent)
+    return;
   fetchEvent->onNavigationPreloadError(
       workerGlobalScope()->scriptController()->getScriptState(),
       std::move(error));
 }
 
 void ServiceWorkerGlobalScopeProxy::dispatchForeignFetchEvent(
     int fetchEventID,
     const WebServiceWorkerRequest& webRequest) {
   if (!OriginTrials::foreignFetchEnabled(workerGlobalScope())) {
     // If origin trial tokens have expired, or are otherwise no longer valid
@@ skipping 260 matching lines @@
   return *m_document;
 }
 
 ServiceWorkerGlobalScope* ServiceWorkerGlobalScopeProxy::workerGlobalScope()
     const {
   DCHECK(m_workerGlobalScope);
   return m_workerGlobalScope;
 }
 
 }  // namespace blink