Add power-user keyboard mode for ChromeOS with Search key acting as a typical Fn key.

chrome/browser/resources/options/chromeos/keyboard_overlay.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('options', function() {
 
   /**
    * Encapsulated handling of the keyboard overlay.
    * @constructor
    */
   function KeyboardOverlay() {
     options.SettingsDialog.call(this, 'keyboard-overlay',
         loadTimeData.getString('keyboardOverlayTitle'),
         'keyboard-overlay',
         $('keyboard-confirm'), $('keyboard-cancel'));
   }
 
   cr.addSingletonGetter(KeyboardOverlay);
 
   KeyboardOverlay.prototype = {
     __proto__: options.SettingsDialog.prototype,
 
     /**
      * Show/hide the caps lock remapping section.
      * @private
      */
     showCapsLockOptions_: function(show) {
       $('caps-lock-remapping-section').hidden = !show;
     },
+
+    /**
+     * Show/hide the function key remapping section.
+     * @private
+     */
+    showFunctionKeyOptions_: function(show) {
+      $('function-key-remapping-section').hidden = !show;
+    },
   };
 
   // Forward public APIs to private implementations.
   [
     'showCapsLockOptions',
+    'showFunctionKeyOptions',
   ].forEach(function(name) {
     KeyboardOverlay[name] = function() {
       var instance = KeyboardOverlay.getInstance();
       return instance[name + '_'].apply(instance, arguments);
     };
   });
 
   // Export
   return {
     KeyboardOverlay: KeyboardOverlay
   };
 });