[MD settings] help button in content settings site lists

chrome/browser/resources/settings/privacy_page/privacy_page.js

 // Copyright 2015 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.
 
 /**
  * @fileoverview
  * 'settings-privacy-page' is the settings page containing privacy and
  * security settings.
  */
 Polymer({
@@ skipping 77 matching lines @@
   /** @private */
   onClearBrowsingDataTap_: function() {
     settings.navigateTo(settings.Route.CLEAR_BROWSER_DATA);
   },
 
   /** @private */
   onDialogClosed_: function() {
     settings.navigateToPreviousRoute();
   },
 
+  /** @private */
+  onHelpTap_: function() {
+    window.open(
+        'https://support.google.com/chrome/?p=settings_manage_exceptions');
+  },
+
 <if expr="_google_chrome and not chromeos">
   /** @private */
   onMetricsReportingCheckboxTap_: function() {
     var browserProxy = settings.PrivacyPageBrowserProxyImpl.getInstance();
     var enabled = this.$.metricsReportingCheckbox.checked;
     browserProxy.setMetricsReportingEnabled(enabled);
   },
 
   /**
    * @param {!MetricsReporting} metricsReporting
@@ skipping 22 matching lines @@
    * The sub-page title for the site or content settings.
    * @return {string}
    * @private
    */
   siteSettingsPageTitle_: function() {
     return loadTimeData.getBoolean('enableSiteSettings') ?
         loadTimeData.getString('siteSettings') :
         loadTimeData.getString('contentSettings');
   },
 });