service worker: Clarify the navigation preload network error message.

content/browser/service_worker/service_worker_browsertest.cc

Index: content/browser/service_worker/service_worker_browsertest.cc
diff --git a/content/browser/service_worker/service_worker_browsertest.cc b/content/browser/service_worker/service_worker_browsertest.cc
index 4cd88192d634a0a87562082bda0e1a2870e9d2e3..46f11e2440881b709b3f8422236ad769ec416634 100644
--- a/content/browser/service_worker/service_worker_browsertest.cc
+++ b/content/browser/service_worker/service_worker_browsertest.cc
@@ -415,6 +415,12 @@ net::HttpResponseInfo CreateHttpResponseInfo() {
   return info;
 }
 
+const std::string kNavigationPreloadAbortError =
+    "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.";
+
 }  // namespace
 
 class ServiceWorkerBrowserTest : public ContentBrowserTest {
@@ -1901,8 +1907,10 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest, NetworkError) {
   title_watcher.AlsoWaitForTitle(base::ASCIIToUTF16("RESOLVED"));
   NavigateToURL(shell(), page_url);
   EXPECT_EQ(title, title_watcher.WaitAndGetTitle());
-  EXPECT_EQ("NetworkError: Service Worker navigation preload network error.",
-            GetTextContent());
+  std::string expected =
+      "The service worker navigation preload request failed with network error "
+      "code -102.";
+  EXPECT_EQ("NetworkError: " + expected, GetTextContent());
 }
 
 IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,
@@ -1919,7 +1927,7 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,
       kWorkerUrl, kEnableNavigationPreloadScript + kPreloadResponseTestScript,
       "text/javascript");
 
-  EXPECT_EQ("NetworkError: Service Worker navigation preload network error.",
+  EXPECT_EQ("NetworkError: " + kNavigationPreloadAbortError,
             LoadNavigationPreloadTestPage(page_url, worker_url, "REJECTED"));
 }
 
@@ -2039,7 +2047,10 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,
   // According to the spec, multiple Location headers is not an error. So the
   // preloadResponse must be resolved with an opaque redirect response.
   // But Chrome treats multiple Location headers as an error (crbug.com/98895).
-  EXPECT_EQ("NetworkError: Service Worker navigation preload network error.",
+  std::string expected =
+      "The service worker navigation preload request failed with network error "
+      "code -350.";
+  EXPECT_EQ("NetworkError: " + expected,
             LoadNavigationPreloadTestPage(page_url, worker_url, "REJECTED"));
 
   // The page request must be sent only once, since the worker responded with
@@ -2070,7 +2081,7 @@ IN_PROC_BROWSER_TEST_F(ServiceWorkerNavigationPreloadTest,
   // preloadResponse must be resolve with an opaque redirect response. But
   // currently Chrome handles the invalid location URL in the browser process as
   // an error. crbug.com/707185
-  EXPECT_EQ("NetworkError: Service Worker navigation preload network error.",
+  EXPECT_EQ("NetworkError: " + kNavigationPreloadAbortError,
             LoadNavigationPreloadTestPage(page_url, worker_url, "REJECTED"));
 
   // The page request must be sent only once, since the worker responded with