Remove old webui History page on desktop and mobile

chrome/browser/resources/history/history_focus_manager.js

-// Copyright 2013 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 FocusManager = cr.ui.FocusManager;
-
-/**
- * A history-specific FocusManager implementation, which ensures that elements
- * "background" pages (i.e., those in a dialog that is not the topmost overlay)
- * do not receive focus.
- * @constructor
- * @extends {cr.ui.FocusManager}
- */
-function HistoryFocusManager() {
-}
-
-cr.addSingletonGetter(HistoryFocusManager);
-
-HistoryFocusManager.prototype = {
-  __proto__: FocusManager.prototype,
-
-  /** @override */
-  getFocusParent: function() {
-    return document.querySelector('#overlay .showing') ||
-        document.querySelector('cr-menu:not([hidden])') ||
-        $('history-page');
-  },
-};