Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/contextual/src/ContextualController.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\contextual\ContextualController.
+ */
+
+namespace Drupal\contextual;
+
+use Symfony\Component\DependencyInjection\ContainerAwareInterface;
+use Symfony\Component\DependencyInjection\ContainerAwareTrait;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Returns responses for Contextual module routes.
+ */
+class ContextualController implements ContainerAwareInterface {
+
+  use ContainerAwareTrait;
+
+  /**
+   * Returns the requested rendered contextual links.
+   *
+   * Given a list of contextual links IDs, render them. Hence this must be
+   * robust to handle arbitrary input.
+   *
+   * @see contextual_preprocess()
+   *
+   * @return \Symfony\Component\HttpFoundation\JsonResponse
+   *   The JSON response.
+   */
+  public function render(Request $request) {
+    $ids = $request->request->get('ids');
+    if (!isset($ids)) {
+      throw new BadRequestHttpException(t('No contextual ids specified.'));
+    }
+
+    $rendered = array();
+    foreach ($ids as $id) {
+      $element = array(
+        '#type' => 'contextual_links',
+        '#contextual_links' => _contextual_id_to_links($id),
+      );
+      $rendered[$id] = $this->container->get('renderer')->renderRoot($element);
+    }
+
+    return new JsonResponse($rendered);
+  }
+
+}