[MD settings] restore side nav drop icons

chrome/browser/resources/settings/settings_menu/settings_menu.html

 <link rel="import" href="chrome://resources/cr_elements/cr_icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/av-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/device-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/hardware-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/image-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/social-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-menu.html">
@@ skipping 50 matching lines @@
       paper-submenu div {
         @apply(--layout-center);
         -webkit-margin-start: 24px;
         display: flex;
         font-size: 13px;
         font-weight: 500;
         min-height: 40px;
       }
     </style>
     <paper-menu name="root-menu">
-      <paper-submenu data-page="basic" id="basicPage">
+      <paper-submenu data-page="basic" id="basicPage" opened="{{basicOpened_}}">
         <div class="menu-trigger" data-section="" on-tap="openPage_">
           <span i18n-content="basicPageTitle"></span>
           <iron-icon icon="[[arrowState_(basicOpened_)]]" item-icon></iron-icon>
         </div>
         <paper-menu attr-for-selected="data-section" class="menu-content"
             data-page="basic" id="basicMenu">
 <if expr="chromeos">
           <div data-section="internet" on-tap="openPage_">
             <iron-icon icon="device:network-wifi" item-icon></iron-icon>
             <span i18n-content="internetPageTitle"></span>
@@ skipping 22 matching lines @@
             <iron-icon icon="av:web" item-icon></iron-icon>
             <span i18n-content="defaultBrowser"></span>
           </div>
 </if>
           <div data-section="onStartup" on-tap="openPage_">
             <iron-icon icon="icons:power-settings-new" item-icon></iron-icon>
             <span i18n-content="onStartup"></span>
           </div>
         </paper-menu>
       </paper-submenu>
-      <paper-submenu id="advancedPage" data-page="advanced">
+      <paper-submenu id="advancedPage" data-page="advanced"
+          opened="{{advancedOpened_}}">
         <div class="menu-trigger" data-section="" on-tap="openPage_">
           <span i18n-content="advancedPageTitle"></span>
           <iron-icon icon="[[arrowState_(advancedOpened_)]]" item-icon>
           </iron-icon>
         </div>
         <paper-menu attr-for-selected="data-section" class="menu-content"
             data-page="advanced" id="advancedMenu">
 <if expr="chromeos">
           <div data-section="dateTime" on-tap="openPage_">
             <iron-icon icon="device:access-time" item-icon></iron-icon>
@@ skipping 40 matching lines @@
       </paper-submenu>
       <paper-submenu on-tap="openPage_">
         <div class="menu-trigger">
           <span i18n-content="aboutProgram"></span>
         </div>
       </paper-submenu>
     </paper-menu>
   </template>
   <script src="settings_menu.js"></script>
 </dom-module>