Sync promo: Only show skip button on startup

chrome/browser/resources/sync_promo/sync_promo.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.
 
 // TODO(sail): Refactor options_page and remove this include.
 <include src="../options/options_page.js"/>
+<include src="../shared/js/util.js"/>
 <include src="../sync_setup_overlay.js"/>
 
 cr.define('sync_promo', function() {
   /**
    * SyncPromo class
    * Subclass of options.SyncSetupOverlay that customizes the sync setup
    * overlay for use in the new tab page.
    * @class
    */
   function SyncPromo() {
@@ skipping 108 matching lines @@
         advancedOptionsClickedAlready = true;
       });
 
       // Re-used across both cancel buttons after a successful sign in.
       var cancelFunc = function() {
         chrome.send('SyncPromo:UserFlowAction',
                     [actions.CANCELLED_AFTER_SIGN_IN]);
       };
       $('confirm-everything-cancel').addEventListener('click', cancelFunc);
       $('choose-datatypes-cancel').addEventListener('click', cancelFunc);
+
+      // Add the source parameter to the document so that it can be used to
+      // selectively show and hide elements using CSS.
+      var params = parseQueryParams(document.location);
+      if (params.source == '0')
+        document.documentElement.setAttribute('isstartup', '');
     },
 
     /**
      * Called when the page is unloading to record number of times a user tried
      * to sign in and if they left while a throbber was running.
      * @private
      */
     recordPageViewActions_: function() {
       chrome.send('SyncPromo:RecordSignInAttempts', [this.signInAttempts_]);
       if (this.throbberStart_)
@@ skipping 79 matching lines @@
   return {
     SyncPromo: SyncPromo
   };
 });
 
 var OptionsPage = options.OptionsPage;
 var SyncSetupOverlay = sync_promo.SyncPromo;
 window.addEventListener('DOMContentLoaded', sync_promo.SyncPromo.initialize);
 window.addEventListener('beforeunload',
     sync_promo.SyncPromo.recordPageViewActions.bind(sync_promo.SyncPromo));