[ServiceWorker] Return abort for browser shutdown during registration.

When a worker is registered while the browser context is shutting down
we return kErrorStartWorkerFailed. This appears to be a mistake since
worker unregistration and start worker requests will kErrorAbort in this
same situation instead.

Worker registration requests will eventually start the worker, so
kErrorStartWorkerFailed is eventually expected if the worker does fail
to start during registration, but not immediately after a worker
registration request is sent.

Bug: 346732739
Change-Id: I4f831bf7a561b79364d6903e9c51e8dc86a380c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5833537
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Justin Lulejian <jlulejian@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1352301}

content/browser/service_worker/service_worker_context_wrapper.cc

@@ -582,10 +582,8 @@ void ServiceWorkerContextWrapper::RegisterServiceWorker(
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (!context_core_) {
     GetUIThreadTaskRunner({})->PostTask(
-        FROM_HERE,
-        base::BindOnce(
-            std::move(callback),
-            blink::ServiceWorkerStatusCode::kErrorStartWorkerFailed));
+        FROM_HERE, base::BindOnce(std::move(callback),
+                                  blink::ServiceWorkerStatusCode::kErrorAbort));
     return;
   }
   blink::mojom::ServiceWorkerRegistrationOptions options_to_pass(