diff --git a/core/modules/system/lib/Drupal/system/Controller/SystemController.php b/core/modules/system/lib/Drupal/system/Controller/SystemController.php
index 6145a11..10b44fa 100644
--- a/core/modules/system/lib/Drupal/system/Controller/SystemController.php
+++ b/core/modules/system/lib/Drupal/system/Controller/SystemController.php
@@ -153,12 +153,4 @@ public function themesPage() {
     return system_themes_page();
   }
 
-  /**
-   * @todo Remove system_theme_default().
-   */
-  public function themeSetDefault() {
-    module_load_include('admin.inc', 'system');
-    return system_theme_default();
-  }
-
 }
diff --git a/core/modules/system/lib/Drupal/system/Controller/ThemeController.php b/core/modules/system/lib/Drupal/system/Controller/ThemeController.php
index 353317f..c397612 100644
--- a/core/modules/system/lib/Drupal/system/Controller/ThemeController.php
+++ b/core/modules/system/lib/Drupal/system/Controller/ThemeController.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Extension\ThemeHandlerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Drupal\Core\Access\CsrfTokenGenerator;
 use Symfony\Component\HttpFoundation\Request;
@@ -21,48 +22,46 @@
 class ThemeController extends ControllerBase implements ContainerInjectionInterface {
 
   /**
-   * Token generator service.
-   *
-   * @var \Drupal\Core\Access\CsrfTokenGenerator
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   *   The theme handler.
    */
-  protected $tokenGenerator;
+  protected $themeHandler;
 
   /**
    * {@inheritdoc}
    */
   public static function create(ContainerInterface $container) {
     return new static(
-      $container->get('csrf_token')
+      $container->get('theme_handler')
     );
   }
 
   /**
    * Constructs a Theme Controller Object.
    *
-   * @param \Drupal\Core\Access\CsrfTokenGenerator $token_generator
-   *   Token Generator Service.
+   * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
+   *   The theme handler.
    */
-  public function __construct(CsrfTokenGenerator $token_generator) {
-    $this->tokenGenerator = $token_generator;
+  public function __construct(ThemeHandlerInterface $theme_handler) {
+    $this->themeHandler = $theme_handler;
   }
+
   /**
    * Disables a theme.
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
-   *   A request object containing a theme name and a valid token.
+   *   A request object containing a theme name.
    *
    * @return \Symfony\Component\HttpFoundation\RedirectResponse
    *   Redirects back to the appearance admin page.
    *
    * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
-   *   Throws access denied when no theme or token is set in the request or when
-   *   the token is invalid.
+   *   Throws access denied when no theme set in the request
    */
   public function disable(Request $request) {
     $theme = $request->get('theme');
-    $token = $request->get('token');
     $config = $this->config('system.theme');
-    if (isset($theme) && isset($token) && $this->tokenGenerator->validate($token, 'system-theme-operation-link')) {
+    if (isset($theme)) {
       // Get current list of themes.
       $themes = list_themes();
 
@@ -73,12 +72,12 @@ public function disable(Request $request) {
           drupal_set_message($this->t('%theme is the default theme and cannot be disabled.', array('%theme' => $themes[$theme]->info['name'])), 'error');
         }
         else {
-          theme_disable(array($theme));
+          $this->themeHandler->disable(array($theme));
           drupal_set_message($this->t('The %theme theme has been disabled.', array('%theme' => $themes[$theme]->info['name'])));
         }
       }
 
-      return new RedirectResponse($this->urlGenerator()->generateFromPath('admin/appearance', array('absolute' => TRUE)));
+      return $this->redirect('system.themes_page');
     }
 
     throw new AccessDeniedHttpException();
@@ -88,35 +87,32 @@ public function disable(Request $request) {
    * Enables a theme.
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
-   *   A request object containing a theme name and a valid token.
+   *   A request object containing a theme name.
    *
    * @return \Symfony\Component\HttpFoundation\RedirectResponse
    *   Redirects back to the appearance admin page.
    *
    * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
-   *   Throws access denied when no theme or token is set in the request or when
-   *   the token is invalid.
+   *   Throws access denied when no theme is set in the request.
    */
   public function enable(Request $request) {
     $theme = $request->get('theme');
-    $token = $request->get('token');
-    $config = $this->config('system.theme');
 
-    if (isset($theme) && isset($token) && $this->tokenGenerator->validate($token, 'system-theme-operation-link')) {
+    if (isset($theme)) {
       // Get current list of themes.
       $themes = list_themes(TRUE);
 
       // Check if the specified theme is one recognized by the system.
       if (!empty($themes[$theme])) {
-        theme_enable(array($theme));
+        $this->themeHandler->enable(array($theme));
         drupal_set_message($this->t('The %theme theme has been enabled.', array('%theme' => $themes[$theme]->info['name'])));
       }
       else {
         drupal_set_message($this->t('The %theme theme was not found.', array('%theme' => $theme)), 'error');
       }
 
-      // @todo switch to $this->redirect when admin/appearance converted.
-      return new RedirectResponse($this->urlGenerator()->generateFromPath('admin/appearance', array('absolute' => TRUE)));
+      return $this->redirect('system.themes_page');
+
     }
 
     throw new AccessDeniedHttpException();
@@ -126,21 +122,19 @@ public function enable(Request $request) {
    * Set the default theme.
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
-   *   A request object containing a theme name and a valid token.
+   *   A request object containing a theme name.
    *
    * @return \Symfony\Component\HttpFoundation\RedirectResponse
    *   Redirects back to the appearance admin page.
    *
    * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
-   *   Throws access denied when no theme or token is set in the request or when
-   *   the token is invalid.
+   *   Throws access denied when no theme is set in the request.
    */
   public function defaultTheme(Request $request) {
     $config = $this->config('system.theme');
-
     $theme = $request->query->get('theme');
-    $token = $request->query->get('token');
-    if (isset($theme) && isset($token) && $this->tokenGenerator->validate($token, 'system-theme-operation-link')) {
+
+    if (isset($theme)) {
       // Get current list of themes.
       $themes = list_themes();
 
@@ -148,22 +142,23 @@ public function defaultTheme(Request $request) {
       if (!empty($themes[$theme])) {
         // Enable the theme if it is currently disabled.
         if (empty($themes[$theme]->status)) {
-          theme_enable(array($theme));
+          $this->themeHandler->enable(array($theme));
         }
 
         // Set the default theme.
         $config->set('default', $theme)->save();
 
         // Rebuild the menu. This duplicates the menu_router_rebuild() in
-        // theme_enable(). However, modules must know the current default theme in
-        // order to use this information in hook_menu() or hook_menu_alter()
-        // implementations, and doing the variable_set() before the theme_enable()
-        // could result in a race condition where the theme is default but not
-        // enabled.
+        // theme_enable(). However, modules must know the current default theme
+        // in order to use this information in hook_menu() or hook_menu_alter()
+        // implementations, and doing the variable_set() before the
+        // theme_enable() could result in a race condition where the theme is
+        // default but not enabled.
         menu_router_rebuild();
 
-        // The status message depends on whether an admin theme is currently in use:
-        // a value of 0 means the admin theme is set to be the default theme.
+        // The status message depends on whether an admin theme is currently in
+        // use: a value of 0 means the admin theme is set to be the default
+        // theme.
         $admin_theme = $config->get('admin');
         if ($admin_theme != 0 && $admin_theme != $theme) {
           drupal_set_message($this->t('Please note that the administration theme is still set to the %admin_theme theme; consequently, the theme on this page remains unchanged. All non-administrative sections of the site, however, will show the selected %selected_theme theme by default.', array(
@@ -178,8 +173,9 @@ public function defaultTheme(Request $request) {
       else {
         drupal_set_message($this->t('The %theme theme was not found.', array('%theme' => $theme)), 'error');
       }
-      // @todo switch to $this->redirect when admin/appearance converted.
-      return new RedirectResponse($this->urlGenerator()->generateFromPath('admin/appearance', array('absolute' => TRUE)));
+
+      return $this->redirect('system.themes_page');
+
     }
     throw new AccessDeniedHttpException();
   }
diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 726d965..241ca20 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -185,59 +185,6 @@ function system_themes_admin_form_submit($form, &$form_state) {
 }
 
 /**
- * Menu callback; Set the default theme.
- */
-function system_theme_default() {
-  $request = \Drupal::request();
-  $theme = $request->get('theme');
-  if (!empty($theme)) {
-    // Get current list of themes.
-    $themes = list_themes();
-
-    // Check if the specified theme is one recognized by the system.
-    if (!empty($themes[$theme])) {
-      // Enable the theme if it is currently disabled.
-      if (empty($themes[$theme]->status)) {
-       theme_enable(array($theme));
-      }
-      // Set the default theme.
-      \Drupal::config('system.theme')
-        ->set('default', $theme)
-        ->save();
-
-      // Rebuild the menu. This duplicates the menu_router_rebuild() in
-      // theme_enable(). However, modules must know the current default theme in
-      // order to use this information in hook_menu() or hook_menu_alter()
-      // implementations, and doing the variable_set() before the theme_enable()
-      // could result in a race condition where the theme is default but not
-      // enabled.
-      \Drupal::service('router.builder')->rebuild();
-      menu_router_rebuild();
-      \Drupal::cache('cache')->deleteTags(array('local_task' => 1));
-
-      // The status message depends on whether an admin theme is currently in use:
-      // a value of 0 means the admin theme is set to be the default theme.
-      $admin_theme = \Drupal::config('system.theme')->get('admin');
-      if ($admin_theme != 0 && $admin_theme != $theme) {
-        drupal_set_message(t('Please note that the administration theme is still set to the %admin_theme theme; consequently, the theme on this page remains unchanged. All non-administrative sections of the site, however, will show the selected %selected_theme theme by default.', array(
-          '%admin_theme' => $themes[$admin_theme]->info['name'],
-          '%selected_theme' => $themes[$theme]->info['name'],
-        )));
-      }
-      else {
-        drupal_set_message(t('%theme is now the default theme.', array('%theme' => $themes[$theme]->info['name'])));
-      }
-    }
-    else {
-      drupal_set_message(t('The %theme theme was not found.', array('%theme' => $theme)), 'error');
-    }
-    return new RedirectResponse(url('admin/appearance', array('absolute' => TRUE)));
-  }
-  throw new AccessDeniedHttpException();
-  Drupal::config('system.theme')->set('admin', $form_state['values']['admin_theme'])->save();
-}
-
-/**
  * Recursively check compatibility.
  *
  * @param $incompatible
diff --git a/core/modules/system/system.routing.yml b/core/modules/system/system.routing.yml
index 25108ce..a770d97 100644
--- a/core/modules/system/system.routing.yml
+++ b/core/modules/system/system.routing.yml
@@ -319,7 +319,7 @@ system.theme_set_default:
   path: '/admin/appearance/default'
   defaults:
     _title: 'Set default theme'
-    _content: '\Drupal\system\Controller\SystemController::themeSetDefault'
+    _content: '\Drupal\system\Controller\ThemeController::defaultTheme'
   requirements:
     _permission: 'administer themes'
     _csrf_token: 'TRUE'