MD Settings: Restore focus after exiting Content settings sub-subpages.

chrome/browser/resources/settings/privacy_page/privacy_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_vars_css.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout-classes.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="../clear_browsing_data_dialog/clear_browsing_data_dialog.html">
@@ skipping 203 matching lines @@
           </settings-certificate-manager-page>
         </settings-subpage>
       </template>
 </if>
       <template is="dom-if" route-path="/content">
         <settings-subpage
             associated-control="[[$$('#site-settings-subpage-trigger')]]"
             id="site-settings"
             page-title="[[siteSettingsPageTitle_()]]"
             learn-more-url="$i18n{exceptionsLearnMoreURL}">
-          <settings-site-settings-page></settings-site-settings-page>
+          <settings-site-settings-page focus-config="[[focusConfig_]]">
+          </settings-site-settings-page>
         </settings-subpage>
       </template>
 
       <template is="dom-if" route-path="/content/all" no-search>
         <settings-subpage page-title="$i18n{siteSettingsCategoryAllSites}">
           <all-sites></all-sites>
         </settings-subpage>
       </template>
       <template is="dom-if" route-path="/content/automaticDownloads" no-search>
         <settings-subpage page-title="$i18n{siteSettingsAutomaticDownloads}">
@@ skipping 252 matching lines @@
                 category="{{ContentSettingsTypes.PROTECTED_CONTENT}}">
             </category-setting-exceptions>
           </template>
 </if>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="privacy_page.js"></script>
 </dom-module>