MD Settings: Custom expand/collapse section animations.

chrome/browser/resources/settings/settings_main/settings_main.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-main' displays the selected settings page.
  *
  * Example:
  *
@@ skipping 25 matching lines @@
       observer: 'currentRouteChanged_',
     },
 
     // If false the 'basic' page should be shown.
     showAdvancedPage_: {
       type: Boolean,
       value: false
     }
   },
 
-  listeners: {
-    'expand-animation-complete': 'onExpandAnimationComplete_',
-  },
-
   /** @private */
   currentRouteChanged_: function(newRoute, oldRoute) {
     this.showAdvancedPage_ = newRoute.page == 'advanced';
-
-    var pageContainer = this.$.pageContainer;
-    if (!oldRoute) {
-      pageContainer.classList.toggle('expanded', newRoute.section);
-      return;
-    }
-
-    // For contraction only, apply new styling immediately.
-    if (!newRoute.section && oldRoute.section) {
-      pageContainer.classList.remove('expanded');
-
-      // TODO(tommycli): Save and restore scroll position. crbug.com/537359.
-      pageContainer.scrollTop = 0;
-    }
-  },
-
-  /** @private */
-  onExpandAnimationComplete_: function() {
-    if (this.currentRoute.section) {
-      var pageContainer = this.$.pageContainer;
-      pageContainer.classList.add('expanded');
-      pageContainer.scrollTop = 0;
-    }
   },
 });