service worker: Clarify the navigation preload network error message.

content/renderer/service_worker/service_worker_context_client.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/service_worker/service_worker_context_client.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/lazy_instance.h"
@@ skipping 33 matching lines @@
 #include "content/public/renderer/document_state.h"
 #include "content/renderer/devtools/devtools_agent.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/renderer/service_worker/embedded_worker_devtools_agent.h"
 #include "content/renderer/service_worker/embedded_worker_dispatcher.h"
 #include "content/renderer/service_worker/embedded_worker_instance_client_impl.h"
 #include "content/renderer/service_worker/service_worker_type_converters.h"
 #include "content/renderer/service_worker/service_worker_type_util.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
+#include "net/base/net_errors.h"
 #include "net/http/http_response_headers.h"
 #include "third_party/WebKit/public/platform/URLConversion.h"
 #include "third_party/WebKit/public/platform/WebMessagePortChannel.h"
 #include "third_party/WebKit/public/platform/WebReferrerPolicy.h"
 #include "third_party/WebKit/public/platform/WebSecurityOrigin.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebURLResponse.h"
 #include "third_party/WebKit/public/platform/modules/background_fetch/WebBackgroundFetchSettledFetch.h"
 #include "third_party/WebKit/public/platform/modules/notifications/WebNotificationData.h"
 #include "third_party/WebKit/public/platform/modules/payments/WebPaymentAppRequest.h"
@@ skipping 353 matching lines @@
 
   void OnStartLoadingResponseBody(
       mojo::ScopedDataPipeConsumerHandle body) override {
     DCHECK(!body_.is_valid());
     body_ = std::move(body);
     MaybeReportResponseToClient();
   }
 
   void OnComplete(const ResourceRequestCompletionStatus& status) override {
     if (status.error_code != net::OK) {
+      std::string message;
+      std::string unsanitized_message;
+      if (status.error_code == net::ERR_ABORTED) {
+        message =
+            "The service worker navigation preload request was cancelled "
+            "before 'preloadResponse' settled. If you intend to use "
+            "'preloadResponse', use waitUntil() or respondWith() to wait for "
+            "the promise to settle.";
+      } else {
+        message =
+            "The service worker navigation preload request failed with a "
+            "network error.";
+        unsanitized_message =
+            "The service worker navigation preload request failed with network "
+            "error: " +
+            net::ErrorToString(status.error_code) + ".";
+      }
+
       // This will delete |this|.
-      ReportErrorToClient("Service Worker navigation preload network error.");
+      ReportErrorToClient(message, unsanitized_message);
       return;
     }
 
     ServiceWorkerContextClient* client =
         ServiceWorkerContextClient::ThreadSpecificInstance();
     if (!client)
       return;
     if (response_) {
       // When the response body from the server is empty, OnComplete() is called
       // without OnStartLoadingResponseBody().
@@ skipping 12 matching lines @@
     ServiceWorkerContextClient* client =
         ServiceWorkerContextClient::ThreadSpecificInstance();
     if (!client)
       return;
 
     client->OnNavigationPreloadResponse(
         fetch_event_id_, std::move(response_),
         base::MakeUnique<WebDataConsumerHandleImpl>(std::move(body_)));
   }
 
-  void ReportErrorToClient(const char* error_message) {
+  void ReportErrorToClient(const std::string& message,
+                           const std::string& unsanitized_message) {
     ServiceWorkerContextClient* client =
         ServiceWorkerContextClient::ThreadSpecificInstance();
     if (!client)
       return;
     // This will delete |this|.
     client->OnNavigationPreloadError(
         fetch_event_id_, base::MakeUnique<blink::WebServiceWorkerError>(
                              blink::WebServiceWorkerError::kErrorTypeNetwork,
-                             blink::WebString::FromUTF8(error_message)));
+                             blink::WebString::FromUTF8(message),
+                             blink::WebString::FromUTF8(unsanitized_message)));
   }
 
   const int fetch_event_id_;
   const GURL url_;
   mojom::URLLoaderPtr url_loader_;
   mojo::Binding<mojom::URLLoaderClient> binding_;
 
   std::unique_ptr<blink::WebURLResponse> response_;
   mojo::ScopedDataPipeConsumerHandle body_;
 };
@@ skipping 1040 matching lines @@
 }
 
 base::WeakPtr<ServiceWorkerContextClient>
 ServiceWorkerContextClient::GetWeakPtr() {
   DCHECK(worker_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(context_);
   return context_->weak_factory.GetWeakPtr();
 }
 
 }  // namespace content