MD Settings/Downloads: show file chooser after CHANGE button ripple completes

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

 // Copyright 2017 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.
 
 /**
  * @constructor
  * @implements {settings.DownloadsBrowserProxy}
  * @extends {settings.TestBrowserProxy}
  */
 var TestDownloadsBrowserProxy = function() {
@@ skipping 43 matching lines @@
   });
 
   teardown(function() {
     downloadsPage.remove();
   });
 
   test('select downloads location', function() {
     var button = downloadsPage.$$('#changeDownloadsPath');
     assertTrue(!!button);
     MockInteractions.tap(button);
+    button.fire('transitionend');
     return DownloadsBrowserProxy.whenCalled('selectDownloadLocation');
   });
 
   test('openAdvancedDownloadsettings', function() {
     var button = downloadsPage.$$('#resetAutoOpenFileTypes');
     assertTrue(!button);
 
     cr.webUIListenerCallback('auto-open-downloads-changed', true);
     Polymer.dom.flush();
     var button = downloadsPage.$$('#resetAutoOpenFileTypes');
     assertTrue(!!button);
 
     MockInteractions.tap(button);
     return DownloadsBrowserProxy.whenCalled('resetAutoOpenFileTypes')
         .then(function() {
           cr.webUIListenerCallback('auto-open-downloads-changed', false);
           Polymer.dom.flush();
           var button = downloadsPage.$$('#resetAutoOpenFileTypes');
           assertTrue(!button);
         });
   });
 });