Disable synchronous XMLHttpRequests in platform app documents.

chrome/test/data/extensions/platform_apps/restrictions/test.js

 // Copyright (c) 2012 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.
 
 var assertEq = chrome.test.assertEq;
 var fail = chrome.test.fail;
 var succeed = chrome.test.succeed;
 
-var error = "Not available for platform apps.";
+var DEFAULT_EXPECTED_ERROR = "Not available for platform apps.";
 
-function assertThrowsError(method) {
+function assertThrowsError(method, opt_expectedError) {
   try {
     method();
     fail("error not thrown");
   } catch (e) {
-    assertEq(e, error);
+    assertEq(e.message || e, opt_expectedError || DEFAULT_EXPECTED_ERROR);
   }
 }
 
 chrome.test.runTests([
   function testDocumentOpen() {
     assertThrowsError(document.open);
     succeed();
   },
 
   function testDocumentClose() {
@@ skipping 79 matching lines @@
   function testBars() {
     var bars = ['locationbar', 'menubar', 'personalbar',
                 'scrollbars', 'statusbar', 'toolbar'];
     for (var x = 0; x < bars.length; x++) {
       assertThrowsError(function() {
         var visible = this[bars[x]].visible;
         visible = window[bars[x]].visible;
       });
     }
     succeed();
+  },
+
+  function testSyncXhr() {
+    var xhr = new XMLHttpRequest();
+    assertThrowsError(function() {
+      xhr.open('GET', 'data:should not load', false);
+    }, 'INVALID_ACCESS_ERR: DOM Exception 15');
+    succeed();
   }
 ]);