Implement ServiceWorkerFetchDispatcher::MaybeStartNavigationPreload().

content/browser/service_worker/service_worker_provider_host.cc

Index: content/browser/service_worker/service_worker_provider_host.cc
diff --git a/content/browser/service_worker/service_worker_provider_host.cc b/content/browser/service_worker/service_worker_provider_host.cc
index d1e82aac54e748d217663ddfb4987b3b756821ad..d20c0652cb7399643aab2dd3eee9923004d59f65 100644
--- a/content/browser/service_worker/service_worker_provider_host.cc
+++ b/content/browser/service_worker/service_worker_provider_host.cc
@@ -341,11 +341,15 @@ ServiceWorkerProviderHost::CreateRequestHandler(
   }
   if (ServiceWorkerUtils::IsMainResourceType(resource_type) ||
       controlling_version()) {
+    // |dispatcher_host_| may be null in some unittests.
     return std::unique_ptr<ServiceWorkerRequestHandler>(
         new ServiceWorkerControlleeRequestHandler(
             context_, AsWeakPtr(), blob_storage_context, request_mode,
             credentials_mode, redirect_mode, resource_type,
-            request_context_type, frame_type, body));
+            request_context_type, frame_type, body,
+            dispatcher_host_ ? dispatcher_host_->url_loader_factory_callback()
+                             : ServiceWorkerControlleeRequestHandler::
+                                   URLLoaderFactoryCallback()));
   }
   return std::unique_ptr<ServiceWorkerRequestHandler>();
 }