diff --git a/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
new file mode 100644
index 0000000..9af654e
--- /dev/null
+++ b/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -0,0 +1,108 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\Component\Plugin\Discovery\AnnotatedClassDiscovery.
+ */
+
+namespace Drupal\Component\Plugin\Discovery;
+
+use DirectoryIterator;
+use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
+use Drupal\Component\Reflection\MockFileFinder;
+use Drupal\Core\Annotation\Plugin;
+use Doctrine\Common\Annotations\AnnotationReader;
+use Doctrine\Common\Annotations\AnnotationRegistry;
+use Doctrine\Common\Reflection\StaticReflectionParser;
+
+/**
+ * Defines a discovery mechanism to find annotated plugins in PSR-0 namespaces.
+ */
+class AnnotatedClassDiscovery implements DiscoveryInterface {
+  protected $owner;
+  protected $type;
+  protected $namespaces;
+  protected $annotation_namespace;
+  protected $annotation_dir;
+  protected $reflection_class;
+
+  /**
+   * Constructs an AnnotatedClassDiscovery object.
+   */
+  function __construct($owner, $type, $namespaces, $annotation_namespace, $annotation_dir, $reflection_class) {
+    $this->owner = $owner;
+    $this->type = $type;
+    $this->namespace_dir = $namespace_dir;
+    $this->namespaces = $namespaces;
+    $this->reflection_class = $reflection_class;
+  }
+
+  /**
+   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
+   */
+  public function getDefinition($plugin_id) {
+    $plugins = $this->getDefinitions();
+    return isset($plugins[$plugin_id]) ? $plugins[$plugin_id] : NULL;
+  }
+
+  /**
+   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
+   */
+  public function getDefinitions() {
+    $definitions = array();
+    $reader = new AnnotationReader();
+    // Prevent @endlink from being parsed as an annotation.
+    $reader->addGlobalIgnoredName('endlink');
+
+    // Register the namespace of classes that can be used for annotations.
+    AnnotationRegistry::registerAutoloadNamespace($this->annotation_namespace, $this->annotation_dir);
+    // Get all PSR-0 namespaces.
+    foreach ($this->namespaces as $ns => $namespace_dirs) {
+
+      // OS-Safe directory separators.
+      $ns = str_replace('\\', DIRECTORY_SEPARATOR, $ns);
+
+      foreach ($namespace_dirs as $dir) {
+        // Check for the pre-determined directory structure to find plugins.
+        $prefix = implode(DIRECTORY_SEPARATOR, array(
+          $ns,
+          'Plugin',
+          $this->owner,
+          $this->type
+        ));
+        $dir .= DIRECTORY_SEPARATOR . $prefix;
+
+        // If the directory structure exists, look for classes.
+        if (file_exists($dir)) {
+          $directories = new DirectoryIterator($dir);
+          foreach ($directories as $fileinfo) {
+            // @todo Once core requires 5.3.6, use $fileinfo->getExtension().
+            if (pathinfo($fileinfo->getFilename(), PATHINFO_EXTENSION) == 'php') {
+              $class = str_replace(
+                DIRECTORY_SEPARATOR,
+                '\\',
+                $prefix . DIRECTORY_SEPARATOR . $fileinfo->getBasename('.php')
+              );
+
+              // The filename is already known, so there is no need to find the
+              // file. However, StaticReflectionParser needs a finder, so use a
+              // mock version.
+              $finder = MockFileFinder::create($fileinfo->getPathName());
+              $parser = new StaticReflectionParser($class, $finder);
+
+              if ($annotation = $reader->getClassAnnotation($parser->getReflectionClass(), $this->reflection_class)) {
+                // AnnotationInterface::get() returns the array definition
+                // instead of requiring us to work with the annotation object.
+                $definition = $annotation->get();
+                $definition['class'] = $class;
+                $definitions[$definition['id']] = $definition;
+              }
+            }
+          }
+        }
+      }
+    }
+    return $definitions;
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
index bd89a92..ab3bb70 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -7,94 +7,24 @@
 
 namespace Drupal\Core\Plugin\Discovery;
 
-use DirectoryIterator;
-use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
-use Drupal\Component\Reflection\MockFileFinder;
-use Drupal\Core\Annotation\Plugin;
-use Doctrine\Common\Annotations\AnnotationReader;
-use Doctrine\Common\Annotations\AnnotationRegistry;
-use Doctrine\Common\Reflection\StaticReflectionParser;
+use Drupal\Component\Plugin\Discovery\AnnotatedClassDiscovery as ComponentAnnotatedClassDiscovery;
 
 /**
  * Defines a discovery mechanism to find annotated plugins in PSR-0 namespaces.
  */
-class AnnotatedClassDiscovery implements DiscoveryInterface {
+class AnnotatedClassDiscovery extends ComponentAnnotatedClassDiscovery {
 
   /**
    * Constructs an AnnotatedClassDiscovery object.
    */
-  function __construct($owner, $type) {
+  function __construct($owner, $type, $namespaces = NULL) {
     $this->owner = $owner;
     $this->type = $type;
-  }
-
-  /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    $plugins = $this->getDefinitions();
-    return isset($plugins[$plugin_id]) ? $plugins[$plugin_id] : NULL;
-  }
-
-  /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
-   */
-  public function getDefinitions() {
-    $definitions = array();
-    $reader = new AnnotationReader();
-    // Prevent @endlink from being parsed as an annotation.
-    $reader->addGlobalIgnoredName('endlink');
-
-    // Register the namespace of classes that can be used for annotations.
-    AnnotationRegistry::registerAutoloadNamespace('Drupal\Core\Annotation', array(DRUPAL_ROOT . '/core/lib'));
-    // Get all PSR-0 namespaces.
-    $namespaces = drupal_classloader()->getNamespaces();
-    foreach ($namespaces as $ns => $namespace_dirs) {
-
-      // OS-Safe directory separators.
-      $ns = str_replace('\\', DIRECTORY_SEPARATOR, $ns);
-
-      foreach ($namespace_dirs as $dir) {
-        // Check for the pre-determined directory structure to find plugins.
-        $prefix = implode(DIRECTORY_SEPARATOR, array(
-          $ns,
-          'Plugin',
-          $this->owner,
-          $this->type
-        ));
-        $dir .= DIRECTORY_SEPARATOR . $prefix;
-
-        // If the directory structure exists, look for classes.
-        if (file_exists($dir)) {
-          $directories = new DirectoryIterator($dir);
-          foreach ($directories as $fileinfo) {
-            // @todo Once core requires 5.3.6, use $fileinfo->getExtension().
-            if (pathinfo($fileinfo->getFilename(), PATHINFO_EXTENSION) == 'php') {
-              $class = str_replace(
-                DIRECTORY_SEPARATOR,
-                '\\',
-                $prefix . DIRECTORY_SEPARATOR . $fileinfo->getBasename('.php')
-              );
-
-              // The filename is already known, so there is no need to find the
-              // file. However, StaticReflectionParser needs a finder, so use a
-              // mock version.
-              $finder = MockFileFinder::create($fileinfo->getPathName());
-              $parser = new StaticReflectionParser($class, $finder);
-
-              if ($annotation = $reader->getClassAnnotation($parser->getReflectionClass(), 'Drupal\Core\Annotation\Plugin')) {
-                // AnnotationInterface::get() returns the array definition
-                // instead of requiring us to work with the annotation object.
-                $definition = $annotation->get();
-                $definition['class'] = $class;
-                $definitions[$definition['id']] = $definition;
-              }
-            }
-          }
-        }
-      }
+    if (empty($namespaces)) {
+      $this->namespaces = drupal_classloader()->getNamespaces();
     }
-    return $definitions;
+    $this->annotation_namespace = 'Drupal\Core\Annotation';
+    $this->annotation_dir = array(DRUPAL_ROOT . '/core/lib');
+    $this->reflection_class = 'Drupal\Core\Annotation\Plugin';
   }
-
 }