Failure in reading Blob URL should results in network error

chrome/test/data/extensions/api_test/mime_handler_view/index.js

 // Copyright 2014 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.
 
 'use strict';
 
 // Tests don't start running until an async call to
 // chrome.mimeHandlerPrivate.getStreamInfo() completes, so queue any messages
 // received until that point.
 var queuedMessages = [];
 
 function queueMessage(event) {
   queuedMessages.push(event);
 }
 
 window.addEventListener('message', queueMessage, false);
 
 var streamDetails;
 
 function fetchUrl(url) {
   return new Promise(function(resolve, reject) {
     var request = new XMLHttpRequest();
-    request.onreadystatechange = function() {
+    request.onload = function() {
       if (request.readyState == 4) {
         resolve({
           status: request.status,
           data: request.responseText,
         });
       }
     };
+    request.onerror = function(e) {
+      // Network error.
+      resolve({
+        status: request.status,
+        data: 'error',
+      });
+    }
     request.open('GET', streamDetails.streamUrl, true);
     request.send();
   });
 }
 
 function expectSuccessfulRead(response) {
   chrome.test.assertEq(200, response.status);
   chrome.test.assertEq('content to read\n', response.data);
 }
 
@@ skipping 40 matching lines @@
     });
     var contentRead = fetchUrl(streamDetails.streamUrl)
         .then(expectSuccessfulRead);
     Promise.all([printMessageArrived, contentRead]).then(chrome.test.succeed);
   },
 
   function testAbort() {
     checkStreamDetails('testAbort.csv', false);
     chrome.mimeHandlerPrivate.abortStream(function() {
       fetchUrl(streamDetails.streamUrl).then(function(response) {
-        chrome.test.assertEq(404, response.status);
-        chrome.test.assertEq('', response.data);
+        chrome.test.assertEq(0, response.status);
+        chrome.test.assertEq('error', response.data);
         chrome.test.succeed();
       });
     });
   },
 
   function testNonAsciiHeaders() {
     checkStreamDetails('testNonAsciiHeaders.csv', false);
     chrome.test.assertEq(undefined,
                          streamDetails.responseHeaders['Content-Disposition']);
     chrome.test.assertEq(undefined,
@@ skipping 66 matching lines @@
   // Run the test for data URLs.
   if (streamInfo.originalUrl.startsWith("data:")) {
     window.removeEventListener('message', queueMessage);
     // Long data URLs get truncated.
     if (streamInfo.originalUrl == "data:")
       chrome.test.runTests([testsByName['testDataUrlLong']]);
     else
       chrome.test.runTests([testsByName['testDataUrl']]);
   }
 });