MD Settings: Restore focus after exiting various subpages.

chrome/browser/resources/settings/a11y_page/a11y_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../settings_shared_css.html">
 
 <if expr="chromeos">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="manage_a11y_page.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
 <link rel="import" href="../settings_page/settings_animated_pages.html">
 <link rel="import" href="../settings_page/settings_subpage.html">
 </if>
 
 <dom-module id="settings-a11y-page">
   <template>
     <style include="settings-shared"></style>
 <if expr="chromeos">
     <settings-animated-pages id="pages" current-route="{{currentRoute}}"
-        section="a11y">
+        section="a11y" focus-config="[[focusConfig_]]">
       <neon-animatable route-path="default">
         <div class="settings-box">
           <settings-toggle-button id="optionsInMenuToggle"
               label="$i18n{optionsInMenuLabel}"
               pref="{{prefs.settings.a11y.enable_menu}}">
           </settings-toggle-button>
         </div>
         <div id="subpage-trigger" class="settings-box two-line"
             on-tap="onManageAccessibilityFeaturesTap_" actionable>
           <div class="start">
@@ skipping 30 matching lines @@
       </div>
       <button class="icon-external" is="paper-icon-button-light"
           aria-label="$i18n{moreFeaturesLink}"
           aria-describedby="moreFeaturesSecondary"></button>
     </div>
 </if>
 
   </template>
   <script src="a11y_page.js"></script>
 </dom-module>