MD Settings: fix collapse animation once and for all

chrome/browser/resources/settings/settings_main/settings_main.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/promise_resolver.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="/about_page/about_page.html">
 <link rel="import" href="/advanced_page/advanced_page.html">
 <link rel="import" href="/basic_page/basic_page.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_page/main_page_behavior.html">
 <link rel="import" href="/settings_vars_css.html">
@@ skipping 41 matching lines @@
         margin-bottom: 10px;
       }
     </style>
     <content select="paper-icon-button"></content>
     <div id="noSearchResults" hidden$="[[!showNoResultsFound_]]">
       <div>$i18n{searchNoResults}</div>
       <div>$i18nRaw{searchNoResultsHelp}</div>
     </div>
     <template is="dom-if" if="[[showPages_.basic]]">
       <settings-basic-page prefs="{{prefs}}"
-          page-visibility="[[pageVisibility]]">
+          page-visibility="[[pageVisibility]]"
+          on-subpage-expand="onSubpageExpand_">
       </settings-basic-page>
     </template>
     <template is="dom-if"
         if="[[showAdvancedSettings_(pageVisibility.advancedSettings)]]">
       <template is="dom-if" if="[[showAdvancedToggle_(
-          showPages_.basic, inSubpage_, previousShowPages_)]]">
+          showPages_.basic, hasExpandedSection_, previousShowPages_)]]">
         <div id="toggleSpacer"></div>
         <div id="toggleContainer">
           <div id="advancedToggle" on-tap="toggleAdvancedPage_">
             <span>$i18n{advancedPageTitle}</span>
             <iron-icon icon="[[arrowState_(showPages_.advanced)]]"></iron-icon>
           </div>
         </div>
       </template>
       <template is="dom-if" if="[[showPages_.advanced]]">
         <settings-advanced-page prefs="{{prefs}}"
-            page-visibility="[[pageVisibility]]">
+            page-visibility="[[pageVisibility]]"
+            on-subpage-expand="onSubpageExpand_">
         </settings-advanced-page>
       </template>
     </template>
     <template is="dom-if" if="[[showPages_.about]]">
       <settings-about-page></settings-about-page>
     </template>
     <div id="overscroll" style="padding-bottom: [[overscroll_]]px"></div>
   </template>
   <script src="settings_main.js"></script>
   <script src="/search_settings.js"></script>
 </dom-module>