Implements a focus manager for the extensions page.

chrome/browser/resources/extensions/extension_focus_manager.js

+// Copyright (c) 2012 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('extensions', function() {
+  var FocusManager = cr.ui.FocusManager;
+
+  function ExtensionFocusManager() {
+  }
+
+  cr.addSingletonGetter(ExtensionFocusManager);
+
+  ExtensionFocusManager.prototype = {
+    __proto__: FocusManager.prototype,
+
+    /**
+     * Returns the parent element containing all elements which should be
+     * allowed to receive focus.
+     * @return {Element} The element containing focusable elements.
+     */
+    getFocusParent: function() {
+      var overlay = extensions.ExtensionSettings.getCurrentOverlay();
+      return overlay ? overlay : $('extension-settings');

[Evan Stade, 2012/05/31 17:02:00]

you can just do

  return overlay || $('extension-settings');

because JavaScript is cool like that.

[Kyle Horimoto, 2012/06/01 00:02:43]

Done.

+    },
+  };
+
+  return {
+    ExtensionFocusManager: ExtensionFocusManager,
+  };
+});