MD Downloads: use "big search" box like MD history

chrome/test/data/webui/md_history/history_drawer_test.js

 // Copyright 2016 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.
 
 cr.define('md_history.history_drawer_test', function () {
   function registerTests() {
     suite('drawer-test', function() {
       var app;
-      var menuButton;
 
       suiteSetup(function() {
         app = $('history-app');
-        menuButton = app.$.toolbar.$['main-toolbar'].$.menuButton;
       });
 
       test('drawer has correct selection', function() {
         app.selectedPage_ = 'syncedTabs';
         app.hasDrawer_ = true;
         return flush().then(function() {
           var drawer = app.$$('#drawer');
           var drawerSideBar = app.$$('#drawer-side-bar');
 
           assertTrue(!!drawer);
           assertTrue(!!drawerSideBar);
+
+          var menuButton = app.$.toolbar.$['main-toolbar'].$$('#menuButton');
+          assertTrue(!!menuButton);
+
           MockInteractions.tap(menuButton);
           assertTrue(drawer.opened);
 
           assertEquals('syncedTabs', drawerSideBar.$.menu.selected);
         });
       });
     });
   }
 
   return {
     registerTests: registerTests
   };
 });