Remove 'Enable tap-to-click' checkbox for non-touchpad devices.

chrome/browser/resources/options/chromeos/system_options.js

 // Copyright (c) 2011 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() {
 
   var OptionsPage = options.OptionsPage;
   /////////////////////////////////////////////////////////////////////////////
   // SystemOptions class:
 
@@ skipping 118 matching lines @@
    */
   SystemOptions.SetAccessibilityCheckboxState = function(checked) {
     $('accesibility-check').checked = checked;
   };
 
   /**
    * Activate the bluetooth settings section on the System settings page.
    */
   SystemOptions.showBluetoothSettings = function() {
     $('bluetooth-devices').hidden = false;
-  }
+  };
 
   /**
    * Adds an element to the list of available bluetooth devices.
    * @param{{'deviceName': string,
    *         'deviceId': string,
    *         'deviceType': Constants.DEVICE_TYPE,
    *         'deviceStatus': Constants.DEVICE_STATUS} device
    *     Decription of the bluetooth device.
    */
   SystemOptions.addBluetoothDevice = function(device) {
     $('bluetooth-device-list').appendDevice(device);
-  }
+  };
 
   /**
    * Hides the scanning label and icon that are used to indicate that a device
    * search is in progress.
    */
   SystemOptions.notifyBluetoothSearchComplete = function() {
-    // TDOO (kevers) - Reset state immediately once results are received
+    // TODO (kevers) - Reset state immediately once results are received
     //                 asynchronously.
     setTimeout(function() {
       setVisibility_('bluetooth-scanning-label', false);
       setVisibility_('bluetooth-scanning-icon', false);
     }, 2000);
-  }
+  };
+
+  /**
+   * Enables the Tap-To-Click radio button when we detect a touchpad.
+   */
+  SystemOptions.showTapToClick = function() {
+    $('tap-to-click').hidden = false;
+  };
 
   // Export
   return {
     SystemOptions: SystemOptions
   };
 
 });