Increase the lifetime of Navigation Preload related objects.

content/browser/service_worker/service_worker_url_request_job.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 "content/browser/service_worker/service_worker_url_request_job.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 547 matching lines @@
   ServiceWorkerMetrics::RecordActivatedWorkerPreparationTimeForMainFrame(
       worker_ready_time_ - request()->creation_time(), initial_worker_status_,
       version->embedded_worker()->start_situation());
 }
 
 void ServiceWorkerURLRequestJob::DidDispatchFetchEvent(
     ServiceWorkerStatusCode status,
     ServiceWorkerFetchEventResult fetch_result,
     const ServiceWorkerResponse& response,
     const scoped_refptr<ServiceWorkerVersion>& version) {
-  fetch_dispatcher_.reset();
+  // Do not clear |fetch_dispatcher_| if it has dispached a navigation prelaod

[falken, 2017/01/18 14:24:58]

nit: dispatched

[horo, 2017/01/18 16:14:57]

Done.

+  // request to keep the mojom::URLLoader related objects in it.

[falken, 2017/01/18 14:24:58]

Ah, I see... can you add something to the comment like "because the preload
response might still need to be streamed even after calling respondWith()." If
that's correct?

[horo, 2017/01/18 16:14:57]

Yes.
Done.

+  if (!did_navigation_preload_) {
+    fetch_dispatcher_.reset();
+  }
   ServiceWorkerMetrics::RecordFetchEventStatus(IsMainResourceLoad(), status);
 
   ServiceWorkerMetrics::URLRequestJobResult result =
       ServiceWorkerMetrics::REQUEST_JOB_ERROR_BAD_DELEGATE;
   if (!delegate_->RequestStillValid(&result)) {
     RecordResult(result);
     DeliverErrorResponse();
     return;
   }
 
@@ skipping 293 matching lines @@
 
   DCHECK(!fetch_dispatcher_);
   fetch_dispatcher_.reset(new ServiceWorkerFetchDispatcher(
       CreateFetchRequest(), active_worker, resource_type_, timeout_,
       request()->net_log(),
       base::Bind(&ServiceWorkerURLRequestJob::DidPrepareFetchEvent,
                  weak_factory_.GetWeakPtr(), active_worker),
       base::Bind(&ServiceWorkerURLRequestJob::DidDispatchFetchEvent,
                  weak_factory_.GetWeakPtr())));
   worker_start_time_ = base::TimeTicks::Now();
-  fetch_dispatcher_->MaybeStartNavigationPreload(request());
+  did_navigation_preload_ =
+      fetch_dispatcher_->MaybeStartNavigationPreload(request());
   fetch_dispatcher_->Run();
 }
 
 }  // namespace content