Move settings-section animations into setting-section, make better

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.
  */
 Polymer({
   is: 'settings-main',
@@ skipping 75 matching lines @@
 
   /**
    * @param {!SettingsRoute} newRoute
    * @private
    */
   currentRouteChanged_: function(newRoute) {
     var isSubpage = !!newRoute.subpage.length;
 
     this.showAboutPage_ = newRoute.page == 'about';
 
-    this.showAdvancedToggle_ = !this.showAboutPage_ && !isSubpage;
+    this.showAdvancedToggle_ = !this.showAboutPage_;
 
-    this.showBasicPage_ = this.showAdvancedToggle_ || newRoute.page == 'basic';
+    this.showBasicPage_ = !this.showAboutPage_;
 
-    this.showAdvancedPage_ =
+    this.showAdvancedPage_ = this.showAdvancedPage_ ||
         (this.isAdvancedMenuOpen_ && this.showAdvancedToggle_) ||
         newRoute.page == 'advanced';
+  },
 
-    this.style.height = isSubpage ? '100%' : '';
+  subpageExpanded_: function() {
+    this.showBasicPage_ = this.currentRoute.page == 'basic';
+    this.showAdvancedPage_ = !this.showBasicPage_;
+    this.showAdvancedToggle_ = false;
+  },
+
+  subpageCollapsing_: function() {
+    this.currentRouteChanged_(this.currentRoute);
   },
 
   /** @private */
   toggleAdvancedPage_: function() {
     this.fire('toggle-advanced-page', !this.isAdvancedMenuOpen_);
   },
 });