diff --git a/core/lib/Drupal/Core/Entity/AnnotatedClassDiscovery.php b/core/lib/Drupal/Core/Entity/AnnotatedClassDiscovery.php
index d32c571..76b34b2 100644
--- a/core/lib/Drupal/Core/Entity/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Entity/AnnotatedClassDiscovery.php
@@ -7,84 +7,21 @@
 
 namespace Drupal\Core\Entity;
 
-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\Core\Plugin\Discovery\AnnotatedClassDiscoveryBase;
 
 /**
  * Defines a discovery mechanism to find annotated plugins in PSR-0 namespaces.
  */
-class AnnotatedClassDiscovery implements DiscoveryInterface {
+class AnnotatedClassDiscovery extends AnnotatedClassDiscoveryBase {
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
+   * Overrides \Drupal\Core\Plugin\Discovery\AnnotatedClassDiscoveryBase::getDirectoryStructure().
    */
-  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,
-          'EntityType',
-        ));
-        $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;
-              }
-            }
-          }
-        }
-      }
-    }
-    return $definitions;
+  protected function getDirectoryStructure($namespace) {
+    return array(
+      $namespace,
+      'EntityType',
+    );
   }
 
 }
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
index bd89a92..a51758c 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -7,18 +7,10 @@
 
 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;
-
 /**
  * Defines a discovery mechanism to find annotated plugins in PSR-0 namespaces.
  */
-class AnnotatedClassDiscovery implements DiscoveryInterface {
+class AnnotatedClassDiscovery extends AnnotatedClassDiscoveryBase {
 
   /**
    * Constructs an AnnotatedClassDiscovery object.
@@ -29,72 +21,15 @@ function __construct($owner, $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().
+   * Overrides \Drupal\Core\Plugin\Discovery\AnnotatedClassDiscoveryBase::getDirectoryStructure().
    */
-  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;
-              }
-            }
-          }
-        }
-      }
-    }
-    return $definitions;
+  protected function getDirectoryStructure($namespace) {
+    return array(
+      $namespace,
+      'Plugin',
+      $this->owner,
+      $this->type,
+    );
   }
 
 }
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscoveryBase.php
similarity index 85%
copy from core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
copy to core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscoveryBase.php
index bd89a92..f9ce4e2 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscoveryBase.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Definition of Drupal\Core\Plugin\Discovery\AnnotatedClassDiscovery.
+ * Definition of Drupal\Core\Plugin\Discovery\AnnotatedClassDiscoveryBase.
  */
 
 namespace Drupal\Core\Plugin\Discovery;
@@ -18,14 +18,21 @@
 /**
  * Defines a discovery mechanism to find annotated plugins in PSR-0 namespaces.
  */
-class AnnotatedClassDiscovery implements DiscoveryInterface {
+abstract class AnnotatedClassDiscoveryBase implements DiscoveryInterface {
 
   /**
-   * Constructs an AnnotatedClassDiscovery object.
+   * Determines the directory structure under which annotated classes are found.
+   *
+   * @param string $namespace
+   *   The base namespace for this annotated class.
+   *
+   * @return array
+   *   An array whose values are parts of the directory structure.
    */
-  function __construct($owner, $type) {
-    $this->owner = $owner;
-    $this->type = $type;
+  protected function getDirectoryStructure($namespace) {
+    return array(
+      $namespace,
+    );
   }
 
   /**
@@ -54,14 +61,9 @@ public function getDefinitions() {
       // OS-Safe directory separators.
       $ns = str_replace('\\', DIRECTORY_SEPARATOR, $ns);
 
+      $prefix = implode(DIRECTORY_SEPARATOR, $this->getDirectoryStructure($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.