diff --git a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
index 84cb550..ba069d6 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -17,38 +17,25 @@ class AnnotatedClassDiscovery extends ComponentAnnotatedClassDiscovery {
   /**
    * Constructs an AnnotatedClassDiscovery object.
    *
+   * @param string $owner
+   *   The plugin type owner.
+   * @param string $type
+   *   The plugin type name.
+   * @param array $root_namespaces
+   *   Array of root paths keyed by the corresponding namespace to look for
+   *   plugin implementations, \Plugin\$owner\$type will be appended to each
+   *   of those.
    * @param array $plugin_namespaces
    *   An array of paths keyed by it's corresponding namespaces.
    */
-  function __construct($owner, $type, $root_namespaces = NULL, array $plugin_namespaces = array()) {
-    $this->owner = $owner;
-    $this->type = $type;
-    $this->rootNamespaces = $root_namespaces;
-    $this->pluginNamespaces = $plugin_namespaces;
+  function __construct($owner, $type, array $root_namespaces = array(), array $plugin_namespaces = array()) {
+    foreach ($root_namespaces as $namespace => $dir) {
+      $plugin_namespaces["$namespace\\Plugin\\$owner\\$type"] = array($dir);
+    }
     $annotation_namespaces = array(
       'Drupal\Component\Annotation' => DRUPAL_ROOT . '/core/lib',
       'Drupal\Core\Annotation' => DRUPAL_ROOT . '/core/lib',
     );
-    parent::__construct(array(), $annotation_namespaces, 'Drupal\Core\Annotation\Plugin');
+    parent::__construct($plugin_namespaces, $annotation_namespaces, 'Drupal\Core\Annotation\Plugin');
   }
-
-  /**
-   * Overrides Drupal\Component\Plugin\Discovery\AnnotatedClassDiscovery::getPluginNamespaces().
-   *
-   * @todo Figure out how to let this comment still be TRUE.
-   * This is overridden rather than set in the constructor, because Drupal
-   * modules can be enabled (and therefore, namespaces registered) during the
-   * lifetime of a plugin manager.
-   */
-  protected function getPluginNamespaces() {
-    if (!empty($this->plugin_namespaces)) {
-      return parent::getPluginNamespaces();
-    }
-    $plugin_namespaces = array();
-    foreach ($this->rootNamespaces as $namespace => $dir) {
-      $plugin_namespaces["$namespace\\Plugin\\{$this->owner}\\{$this->type}"] = array($dir);
-    }
-    return $plugin_namespaces;
-  }
-
 }