Settings Router Refactor: Remove subpage-back.

chrome/browser/resources/settings/settings_page/settings_animated_pages.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-animated-pages' is a container for a page and animated subpages.
  * It provides a set of common behaviors and animations.
  *
  * Example:
@@ skipping 18 matching lines @@
     section: {
       type: String,
     },
   },
 
   /** @override */
   created: function() {
     // Observe the light DOM so we know when it's ready.
     this.lightDomObserver_ = Polymer.dom(this).observeNodes(
         this.lightDomChanged_.bind(this));
-
-    this.addEventListener('subpage-back', function() {
-      var parent = settings.getCurrentRoute().parent;
-      assert(parent);
-      settings.navigateTo(parent);
-    }.bind(this));
   },
 
   /**
    * Called initially once the effective children are ready.
    * @private
    */
   lightDomChanged_: function() {
     if (this.lightDomReady_)
       return;
 
@@ skipping 91 matching lines @@
     var subpage = /** @type {{_content: DocumentFragment}} */(template)._content
         .querySelector('settings-subpage');
     if (!subpage.id)
       subpage.id = id;
 
     // Render synchronously so neon-animated-pages can select the subpage.
     template.if = true;
     template.render();
   },
 });