Resolve preloadResponse of Navigation Preload even if the response body is empty.

content/renderer/service_worker/service_worker_context_client.cc

Index: content/renderer/service_worker/service_worker_context_client.cc
diff --git a/content/renderer/service_worker/service_worker_context_client.cc b/content/renderer/service_worker/service_worker_context_client.cc
index fb363187fd6025eb3ab42b8b37c010d254d11037..461469d67f79d24bfdfdcb53985c11e0c700cea6 100644
--- a/content/renderer/service_worker/service_worker_context_client.cc
+++ b/content/renderer/service_worker/service_worker_context_client.cc
@@ -364,8 +364,7 @@ class ServiceWorkerContextClient::NavigationPreloadRequest final
         url_loader_(std::move(preload_handle->url_loader)),
         binding_(this, std::move(preload_handle->url_loader_client_request)) {}
 
-  ~NavigationPreloadRequest() override {
-  }
+  ~NavigationPreloadRequest() override {}
 
   void OnReceiveResponse(
       const ResourceResponseHead& response_head,
@@ -421,6 +420,13 @@ class ServiceWorkerContextClient::NavigationPreloadRequest final
         ServiceWorkerContextClient::ThreadSpecificInstance();
     if (!client)
       return;
+    if (response_) {
+      // When the response body from the server is empty, OnComplete() is called
+      // without OnStartLoadingResponseBody().
+      DCHECK(!body_.is_valid());
+      client->OnNavigationPreloadResponse(fetch_event_id_, std::move(response_),
+                                          nullptr);
+    }
     // This will delete |this|.
     client->OnNavigationPreloadComplete(fetch_event_id_);
   }