[Service Worker] Add console message for aborted preload request

When a navigation preload request is aborted, no console message is
sent to the service worker. That's because the "unsanitized_message"
field of blink::WebServiceWorkerError is not set.

When Sending the message to console, prefer the unsanitized one if
avaiable. Update service worker browser test to cover this change.

Bug: 877870
Test: content_browsertests  -gtest_filter=ServiceWorkerNavigationPreloadTest.CanceledByInterceptor
Change-Id: Icad28ce1a9feb40b729bc2504d9c9adb33593a0a
Reviewed-on: https://chromium-review.googlesource.com/1235376
Commit-Queue: Leon Han <leon.han@intel.com>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593823}

AUTHORS

@@ -859,6 +859,7 @@ Tim Niederhausen <tim@rnc-ag.de>
 Timo Gurr <timo.gurr@gmail.com>
 Timo Reimann <ttr314@googlemail.com>
 Timo Witte <timo.witte@gmail.com>
+Ting Shao <ting.shao@intel.com>
 Tom Callaway <tcallawa@redhat.com>
 Tom Harwood <tfh@skip.org>
 Tomas Popela <tomas.popela@gmail.com>

content/browser/service_worker/service_worker_browsertest.cc

@@ -2318,6 +2318,10 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,
     return;
   }
 
+  auto console_observer =
+      base::MakeRefCounted<ConsoleMessageContextObserver>(wrapper());
+  console_observer->Init();
+
   content::ResourceDispatcherHost::Get()->RegisterInterceptor(
       kNavigationPreloadHeaderName, "",
       base::Bind(&CancellingInterceptorCallback));
@@ -2332,6 +2336,11 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,
 
   EXPECT_EQ(kNavigationPreloadAbortError,
             LoadNavigationPreloadTestPage(page_url, worker_url, "REJECTED"));
+
+  console_observer->WaitForConsoleMessages(1);
+  const base::string16 expected = base::ASCIIToUTF16("request was cancelled");
+  std::vector<base::string16> messages = console_observer->messages();
+  EXPECT_NE(base::string16::npos, messages[0].find(expected));
 }
 
 IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,

third_party/blink/renderer/modules/service_worker/service_worker_global_scope_proxy.cc

@@ -435,11 +435,15 @@ void ServiceWorkerGlobalScopeProxy::OnNavigationPreloadError(
   DCHECK(WorkerGlobalScope()->IsContextThread());
   FetchEvent* fetch_event = pending_preload_fetch_events_.Take(fetch_event_id);
   DCHECK(fetch_event);
-  // Display an unsanitized console message.
-  if (!error->unsanitized_message.IsEmpty()) {
+  // Display an error message to the console, preferring the unsanitized one if
+  // available.
+  const WebString& error_message = error->unsanitized_message.IsEmpty()
+                                       ? error->message
+                                       : error->unsanitized_message;
+  if (!error_message.IsEmpty()) {
     WorkerGlobalScope()->AddConsoleMessage(ConsoleMessage::Create(
         kWorkerMessageSource, blink::MessageLevel::kErrorMessageLevel,
-        error->unsanitized_message));
+        error_message));
   }
   // Reject the preloadResponse promise.
   fetch_event->OnNavigationPreloadError(