Fix CrSettingsLanguagesPageTest dialog flake

chrome/test/data/webui/settings/languages_page_tests.js

Index: chrome/test/data/webui/settings/languages_page_tests.js
diff --git a/chrome/test/data/webui/settings/languages_page_tests.js b/chrome/test/data/webui/settings/languages_page_tests.js
index 8bccfad534280762cb873ba0299faaa60d106d9c..b7a5f6ae524c951fd146131c14a70b4c0667689a 100644
--- a/chrome/test/data/webui/settings/languages_page_tests.js
+++ b/chrome/test/data/webui/settings/languages_page_tests.js
@@ -108,9 +108,13 @@ cr.define('languages_page_tests', function() {
       });
 
       // After every test, check that the dialog is removed from the DOM.
-      teardown(function() {
+      teardown(function(done) {
+        // Flush the DOM, then wait for the |restamp| to take effect.
         Polymer.dom.flush();
-        assertEquals(null, languagesPage.$$('settings-add-languages-dialog'));
+        setTimeout(function() {

[dpapad, 2017/05/09 01:14:29]

Nit (optional): Perhaps it would be more robust to listen for a dom-change event
on the dom-if element itself.

[michaelpg, 2017/05/16 00:03:44]

The MutationObserver you suggested in the bug works on the language page's
shadow root - LGTY?

+          assertEquals(null, languagesPage.$$('settings-add-languages-dialog'));
+          done();
+        });
       });
 
       test('cancel', function() {