More Gmail Checker fixes.

chrome/common/extensions/docs/examples/extensions/gmail/options.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.
 
 var customDomainsTextbox;
 var saveButton;
 var cancelButton;
 
 function init() {
   customDomainsTextbox = document.getElementById("custom-domain");
   saveButton = document.getElementById("save-button");
   cancelButton = document.getElementById("cancel-button");
 
   customDomainsTextbox.value = localStorage.customDomain || "";
   markClean();
 }
 
 function getBackgroundPage(callback) {
   if (chrome.runtime) {
     chrome.runtime.getBackgroundPage(callback);
   } else {
     callback(chrome.extension.getBackgroundPage());
   }
 }
 
 function save() {
-  localStorage.customDomain = customDomainsTextbox.value;
+  localStorage.customDomain =
+      customDomainsTextbox.value.replace(/^\/?(.*?)\/?$/, '$1');
   markClean();
   getBackgroundPage(function(backgroundPage) {
     backgroundPage.startRequest({
       scheduleRequest:false,
       showLoadingAnimation:true
     });
   });
 }
 
 function markDirty() {
   saveButton.disabled = false;
 }
 
 function markClean() {
   saveButton.disabled = true;
 }
 
 document.addEventListener('DOMContentLoaded', function () {
   init();
   saveButton.addEventListener('click', save);
   cancelButton.addEventListener('click', init);
   customDomainsTextbox.addEventListener('input', markDirty);
 });