service worker: Clarify the navigation preload network error message.

third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 292 matching lines @@
       std::move(response), std::move(data_consume_handle));
 }
 
 void ServiceWorkerGlobalScopeProxy::OnNavigationPreloadError(
     int fetch_event_id,
     std::unique_ptr<WebServiceWorkerError> error) {
   FetchEvent* fetch_event = pending_preload_fetch_events_.Take(fetch_event_id);
   // This method may be called after onNavigationPreloadResponse() was called.
   if (!fetch_event)
     return;
+  // Display an unsanitized console message.
+  if (!error->unsanitized_message.IsEmpty()) {
+    WorkerGlobalScope()->AddConsoleMessage(ConsoleMessage::Create(
+        kWorkerMessageSource, blink::MessageLevel::kErrorMessageLevel,
+        error->unsanitized_message));
+  }
+  // Reject the preloadResponse promise.
   fetch_event->OnNavigationPreloadError(
       WorkerGlobalScope()->ScriptController()->GetScriptState(),
       std::move(error));
 }
 
 void ServiceWorkerGlobalScopeProxy::DispatchForeignFetchEvent(
     int fetch_event_id,
     const WebServiceWorkerRequest& web_request) {
   if (!OriginTrials::foreignFetchEnabled(WorkerGlobalScope())) {
     // If origin trial tokens have expired, or are otherwise no longer valid
@@ skipping 268 matching lines @@
   return *document_;
 }
 
 ServiceWorkerGlobalScope* ServiceWorkerGlobalScopeProxy::WorkerGlobalScope()
     const {
   DCHECK(worker_global_scope_);
   return worker_global_scope_;
 }
 
 }  // namespace blink