MD Settings: OnStartup, implementing "Edit" functionality.

chrome/browser/resources/settings/on_startup_page/startup_urls_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-startup-urls-page' is the settings page
  * containing the urls that will be opened when chrome is started.
  */
 
 Polymer({
   is: 'settings-startup-urls-page',
 
   behaviors: [WebUIListenerBehavior],
 
   properties: {
     /** @type {settings.StartupUrlsPageBrowserProxy} */
     browserProxy_: Object,
 
     /**
      * Pages to load upon browser startup.
      * @private {!Array<!StartupPageInfo>}
      */
     startupPages_: Array,
 
+    /** @private */
     showStartupUrlDialog_: Boolean,
+
+    /** @private {?StartupPageInfo} */
+    startupUrlDialogModel_: Object,
   },
 
   /** @override */
   attached: function() {
     this.browserProxy_ = settings.StartupUrlsPageBrowserProxyImpl.getInstance();
     this.addWebUIListener('update-startup-pages', function(startupPages) {
       this.startupPages_ = startupPages;
     }.bind(this));
     this.browserProxy_.loadStartupPages();
+
+    this.addEventListener(settings.EDIT_STARTUP_URL_EVENT, function(event) {
+      this.startupUrlDialogModel_ = event.detail;
+      this.openDialog_();
+      event.stopPropagation();
+    }.bind(this));
+  },
+
+  /** @private */
+  onAddPageTap_: function() {
+    this.openDialog_();
   },
 
   /**
    * Opens the dialog and registers a listener for removing the dialog from the
    * DOM once is closed. The listener is destroyed when the dialog is removed
    * (because of 'restamp').
    * @private
    */
-  onAddPageTap_: function() {
+  openDialog_: function() {
     this.showStartupUrlDialog_ = true;
     this.async(function() {
       var dialog = this.$$('settings-startup-url-dialog');
       dialog.addEventListener('iron-overlay-closed', function() {
         this.showStartupUrlDialog_ = false;
+        this.startupUrlDialogModel_ = null;
       }.bind(this));
     }.bind(this));
   },
 
   /** @private */
   onUseCurrentPagesTap_: function() {
     this.browserProxy_.useCurrentPages();
   },
 });