ServiceWorker: Keep the worker alive until FetchEvent.waitUntil settles

content/browser/service_worker/service_worker_fetch_dispatcher.cc

Index: content/browser/service_worker/service_worker_fetch_dispatcher.cc
diff --git a/content/browser/service_worker/service_worker_fetch_dispatcher.cc b/content/browser/service_worker/service_worker_fetch_dispatcher.cc
index dad6fba12ce03423d139ef810c81f696b2e26ac5..a709606092f3254ad8b1c8ececf74c5584e14dd0 100644
--- a/content/browser/service_worker/service_worker_fetch_dispatcher.cc
+++ b/content/browser/service_worker/service_worker_fetch_dispatcher.cc
@@ -10,6 +10,7 @@
 #include "base/trace_event/trace_event.h"
 #include "content/browser/service_worker/service_worker_version.h"
 #include "content/common/service_worker/service_worker_messages.h"
+#include "content/common/service_worker/service_worker_utils.h"
 
 namespace content {
 
@@ -94,13 +95,22 @@ void ServiceWorkerFetchDispatcher::DispatchFetchEvent() {
   base::Closure prepare_callback = prepare_callback_;
   prepare_callback.Run();
 
-  int request_id = version_->StartRequest(
+  int response_request_id = version_->StartRequest(
       GetEventType(), base::Bind(&ServiceWorkerFetchDispatcher::DidFail,
                                  weak_factory_.GetWeakPtr()));
-  version_->DispatchEvent<ServiceWorkerHostMsg_FetchEventFinished>(
-      request_id, ServiceWorkerMsg_FetchEvent(request_id, *request_.get()),
-      base::Bind(&ServiceWorkerFetchDispatcher::DidFinish,
-                 weak_factory_.GetWeakPtr()));
+  int finish_request_id = version_->StartRequest(
+      ServiceWorkerMetrics::EventType::FETCH_WAITUNTIL,
+      base::Bind(&ServiceWorkerUtils::NoOpStatusCallback));
+
+  version_->RegisterRequestCallback<ServiceWorkerHostMsg_FetchEventResponse>(
+      response_request_id, base::Bind(&ServiceWorkerFetchDispatcher::DidFinish,
+                                      weak_factory_.GetWeakPtr()));
+  version_->RegisterSimpleRequest<ServiceWorkerHostMsg_FetchEventFinished>(
+      finish_request_id);
+  version_->DispatchEvent(
+      {response_request_id, finish_request_id},
+      ServiceWorkerMsg_FetchEvent(response_request_id, finish_request_id,
+                                  *request_.get()));
 }
 
 void ServiceWorkerFetchDispatcher::DidPrepare() {