[MD History] Refactor history.html into a history-app element.

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

 // Copyright 2015 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.
 
 /**
  * @fileoverview Test suite for the Material Design history page.
  */
 
 var ROOT_PATH = '../../../../../';
 
@@ skipping 23 matching lines @@
     'history_supervised_user_test.js',
     'history_synced_tabs_test.js',
     'history_toolbar_test.js'
   ]),
 
   /** @override */
   setUp: function() {
     PolymerTest.prototype.setUp.call(this);
 
     suiteSetup(function() {
-      // Wait for each of the top-level elements to be upgraded.
-      return Promise.all([
-        waitForUpgrade($('history-list')),
-        waitForUpgrade($('toolbar')),
-        waitForUpgrade($('history-synced-device-manager')),
-      ]);
+      // Wait for the top-level app element to be upgraded.
+      return waitForUpgrade($('history-app'));
     });
   },
 };
 
 TEST_F('MaterialHistoryBrowserTest', 'HistoryItemTest', function() {
   md_history.history_item_test.registerTests();
   mocha.run();
 });
 
 TEST_F('MaterialHistoryBrowserTest', 'HistoryListTest', function() {
@@ skipping 26 matching lines @@
   testGenPreamble: function() {
     GEN('  SetDeleteAllowed(false);');
   }
 };
 
 TEST_F('MaterialHistoryDeletionDisabledTest', 'HistorySupervisedUserTest',
     function() {
   md_history.history_supervised_user_test.registerTests();
   mocha.run();
 });