[MD settings] Remove old side nav code; remove extra toolbar

chrome/browser/resources/settings/settings_menu/settings_menu.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/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-menu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-submenu.html">
 <link rel="import" href="/icons.html">
 <link rel="import" href="/settings_shared_css.html">
 
 <dom-module id="settings-menu">
   <template>
@@ skipping 12 matching lines @@
         flex: 1;
       }
 
       paper-menu {
         --paper-menu-selected-item: {
           font-weight: 500;
         };
         --paper-menu-focused-item-after: {
           background: none;
         };
-        background: none;  /* Overrides <paper-menu> default. */
         color: var(--settings-nav-grey);
         font-size: 13px;
         padding: 0;
       }
 
       #basicPage {
         margin-top: 8px;
       }
 
       .page-menu > div {
@@ skipping 127 matching lines @@
       <div class="separator"></div>
       <paper-submenu class="page-menu" data-page="about">
         <div class="menu-trigger" on-tap="openPage_" data-section="">
           $i18n{aboutPageTitle}
         </div>
       </paper-submenu>
     </paper-menu>
   </template>
   <script src="settings_menu.js"></script>
 </dom-module>