MD Settings: Creating WebUIListenerBehavior helper.

chrome/browser/resources/settings/search_engines_page/search_engines_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-search-engines-page' is the settings page
  * containing search engines settings.
  *
  * @group Chrome Settings Elements
  * @element settings-search-engines-page
  */
 Polymer({
   is: 'settings-search-engines-page',
 
+  behaviors: [settings.WebUIListenerBehavior],
+
   properties: {
     /** @type {!Array<!SearchEngine>} */
     defaultEngines: {
       type: Array,
       value: function() { return []; }
     },
 
     /** @type {!Array<!SearchEngine>} */
     otherEngines: {
       type: Array,
       value: function() { return []; }
     },
 
     /** @private {boolean} */
     showAddSearchEngineDialog_: Boolean,
 
     /** @private {boolean} */
     otherSearchEnginesExpanded_: {
       type: Boolean,
       value: true,
     },
   },
 
-  /**
-   * Holds WebUI listeners that need to be removed when this element is
-   * destroyed.
-   * TODO(dpapad): Move listener tracking logic to a Polymer behavior class,
-   * such that it can be re-used.
-   * @private {!Array<!WebUIListener>}
-   */
-  webUIListeners_: [],
-
   /** @override */
   ready: function() {
     settings.SearchEnginesBrowserProxyImpl.getInstance().
         getSearchEnginesList().then(this.enginesChanged_.bind(this));
-    this.webUIListeners_.push(cr.addWebUIListener(
-        'search-engines-changed', this.enginesChanged_.bind(this)));
-  },
-
-  /** @override */
-  detached: function() {
-    this.webUIListeners_.forEach(function(listener) {
-      cr.removeWebUIListener(listener);
-    });
+    this.addWebUIListener(
+        'search-engines-changed', this.enginesChanged_.bind(this));
   },
 
   /**
    * @param {!SearchEnginesInfo} searchEnginesInfo
    * @private
    */
   enginesChanged_: function(searchEnginesInfo) {
     this.defaultEngines = searchEnginesInfo['defaults'];
     this.otherEngines = searchEnginesInfo['others'];
     // TODO(dpapad): Use searchEnginesInfo['extensions'] once UI mocks are
     // provided.
   },
 
   /** @private */
   onAddSearchEngineTap_: function() {
     this.showAddSearchEngineDialog_ = true;
     this.async(function() {
       var dialog = this.$$('settings-search-engine-dialog');
       // Register listener to detect when the dialog is closed. Flip the boolean
       // once closed to force a restamp next time it is shown such that the
       // previous dialog's contents are cleared.
       dialog.addEventListener('iron-overlay-closed', function() {
         this.showAddSearchEngineDialog_ = false;
       }.bind(this));
     }.bind(this));
   },
 });