diff --git a/core/modules/system/tests/modules/ajax_test/ajax_test.module b/core/modules/system/tests/modules/ajax_test/ajax_test.module
index 802b34e..1c94a31 100644
--- a/core/modules/system/tests/modules/ajax_test/ajax_test.module
+++ b/core/modules/system/tests/modules/ajax_test/ajax_test.module
@@ -87,100 +87,6 @@ function ajax_test_error() {
 }
 
 /**
- * Menu callback: Renders a form elements and links with #ajax['dialog'].
- *
- * @deprecated \Drupal\ajax_test\Controller\AjaxTestController::dialog()
- */
-function ajax_test_dialog() {
-  // Add two wrapper elements for testing non-modal dialogs. Modal dialogs use
-  // the global drupal-modal wrapper by default.
-  $build['dialog_wrappers'] = array('#markup' => '<div id="ajax-test-dialog-wrapper-1"></div><div id="ajax-test-dialog-wrapper-2"></div>');
-
-  // Dialog behavior applied to a button.
-  $build['form'] = drupal_get_form('ajax_test_dialog_form');
-
-  // Dialog behavior applied to a #type => 'link'.
-  $build['link'] = array(
-    '#type' => 'link',
-    '#title' => 'Link 1 (modal)',
-    '#href' => 'ajax-test/dialog-contents',
-    '#attributes' => array(
-      'class' => array('use-ajax'),
-      'data-accepts' => 'application/vnd.drupal-modal',
-    ),
-  );
-
-  // Dialog behavior applied to links rendered by theme_links().
-  $build['links'] = array(
-    '#theme' => 'links',
-    '#links' => array(
-      'link2' => array(
-        'title' => 'Link 2 (modal)',
-        'href' => 'ajax-test/dialog-contents',
-        'attributes' => array(
-          'class' => array('use-ajax'),
-          'data-accepts' => 'application/vnd.drupal-modal',
-          'data-dialog-options' => json_encode(array(
-            'width' => 400,
-          ))
-        ),
-      ),
-      'link3' => array(
-        'title' => 'Link 3 (non-modal)',
-        'href' => 'ajax-test/dialog-contents',
-        'attributes' => array(
-          'class' => array('use-ajax'),
-          'data-accepts' => 'application/vnd.drupal-dialog',
-          'data-dialog-options' => json_encode(array(
-            'target' => 'ajax-test-dialog-wrapper-1',
-            'width' => 800,
-          ))
-        ),
-      ),
-      'link4' => array(
-        'title' => 'Link 4 (close non-modal if open)',
-        'href' => 'ajax-test/dialog-close',
-        'attributes' => array(
-          'class' => array('use-ajax'),
-        ),
-      ),
-      'link5' => array(
-        'title' => 'Link 5 (form)',
-        'href' => 'ajax-test/dialog-form',
-        'attributes' => array(
-          'class' => array('use-ajax'),
-          'data-accepts' => 'application/vnd.drupal-modal',
-        ),
-      ),
-      'link6' => array(
-        'title' => 'Link 6 (entity form)',
-        'href' => 'admin/structure/contact/add',
-        'attributes' => array(
-          'class' => array('use-ajax'),
-          'data-accepts' => 'application/vnd.drupal-modal',
-          'data-dialog-options' => json_encode(array(
-            'width' => 800,
-            'height' => 500,
-          ))
-        ),
-      ),
-      'link7' => array(
-        'title' => 'Link 7 (non-modal, no target)',
-        'href' => 'ajax-test/dialog-contents',
-        'attributes' => array(
-          'class' => array('use-ajax'),
-          'data-accepts' => 'application/vnd.drupal-dialog',
-          'data-dialog-options' => json_encode(array(
-            'width' => 800,
-          ))
-        ),
-      ),
-    ),
-  );
-  return $build;
-}
-
-/**
  * Form builder: Renders buttons with #ajax['dialog'].
  */
 function ajax_test_dialog_form($form, &$form_state) {
diff --git a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php
index d0387ef..0a6f652 100644
--- a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php
+++ b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php
@@ -43,10 +43,96 @@ public function renderError() {
   }
 
   /**
-   * @todo Remove ajax_test_dialog().
+   * Renders a form elements and links with #ajax['dialog'].
    */
   public function dialog() {
-    return ajax_test_dialog();
+    // Add two wrapper elements for testing non-modal dialogs. Modal dialogs use
+    // the global drupal-modal wrapper by default.
+    $build['dialog_wrappers'] = array('#markup' => '<div id="ajax-test-dialog-wrapper-1"></div><div id="ajax-test-dialog-wrapper-2"></div>');
+
+    // Dialog behavior applied to a button.
+    $build['form'] = drupal_get_form('ajax_test_dialog_form');
+
+    // Dialog behavior applied to a #type => 'link'.
+    $build['link'] = array(
+      '#type' => 'link',
+      '#title' => 'Link 1 (modal)',
+      '#href' => 'ajax-test/dialog-contents',
+      '#attributes' => array(
+        'class' => array('use-ajax'),
+        'data-accepts' => 'application/vnd.drupal-modal',
+      ),
+    );
+
+    // Dialog behavior applied to links rendered by theme_links().
+    $build['links'] = array(
+      '#theme' => 'links',
+      '#links' => array(
+        'link2' => array(
+          'title' => 'Link 2 (modal)',
+          'href' => 'ajax-test/dialog-contents',
+          'attributes' => array(
+            'class' => array('use-ajax'),
+            'data-accepts' => 'application/vnd.drupal-modal',
+            'data-dialog-options' => json_encode(array(
+              'width' => 400,
+            ))
+          ),
+        ),
+        'link3' => array(
+          'title' => 'Link 3 (non-modal)',
+          'href' => 'ajax-test/dialog-contents',
+          'attributes' => array(
+            'class' => array('use-ajax'),
+            'data-accepts' => 'application/vnd.drupal-dialog',
+            'data-dialog-options' => json_encode(array(
+              'target' => 'ajax-test-dialog-wrapper-1',
+              'width' => 800,
+            ))
+          ),
+        ),
+        'link4' => array(
+          'title' => 'Link 4 (close non-modal if open)',
+          'href' => 'ajax-test/dialog-close',
+          'attributes' => array(
+            'class' => array('use-ajax'),
+          ),
+        ),
+        'link5' => array(
+          'title' => 'Link 5 (form)',
+          'href' => 'ajax-test/dialog-form',
+          'attributes' => array(
+            'class' => array('use-ajax'),
+            'data-accepts' => 'application/vnd.drupal-modal',
+          ),
+        ),
+        'link6' => array(
+          'title' => 'Link 6 (entity form)',
+          'href' => 'admin/structure/contact/add',
+          'attributes' => array(
+            'class' => array('use-ajax'),
+            'data-accepts' => 'application/vnd.drupal-modal',
+            'data-dialog-options' => json_encode(array(
+              'width' => 800,
+              'height' => 500,
+            ))
+          ),
+        ),
+        'link7' => array(
+          'title' => 'Link 7 (non-modal, no target)',
+          'href' => 'ajax-test/dialog-contents',
+          'attributes' => array(
+            'class' => array('use-ajax'),
+            'data-accepts' => 'application/vnd.drupal-dialog',
+            'data-dialog-options' => json_encode(array(
+              'width' => 800,
+            ))
+          ),
+        ),
+      ),
+    );
+
+    return $build;
   }
 
   /**