diff --git a/core/core.services.yml b/core/core.services.yml
index 6f8cce6..13c3907 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -487,7 +487,7 @@ services:
       - { name: event_subscriber }
   image.toolkit.manager:
     class: Drupal\system\Plugin\ImageToolkitManager
-    arguments: ['@container.namespaces', '@cache.cache', '@language_manager']
+    arguments: ['@container.namespaces', '@module_handler', '@cache.cache', '@language_manager']
   image.toolkit:
     class: Drupal\system\Plugin\ImageToolkitInterface
     factory_method: getDefaultToolkit
diff --git a/core/lib/Drupal/Core/Archiver/ArchiverManager.php b/core/lib/Drupal/Core/Archiver/ArchiverManager.php
index 14c2a9c..9d206d7 100644
--- a/core/lib/Drupal/Core/Archiver/ArchiverManager.php
+++ b/core/lib/Drupal/Core/Archiver/ArchiverManager.php
@@ -31,8 +31,8 @@ class ArchiverManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Archiver', $namespaces);
-    $this->alterInfo($module_handler, 'archiver_info');
+    parent::__construct('Plugin/Archiver', $namespaces, $module_handler);
+    $this->alterInfo('archiver_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'archiver_info');
   }
 
diff --git a/core/lib/Drupal/Core/Condition/ConditionManager.php b/core/lib/Drupal/Core/Condition/ConditionManager.php
index 7f5d630..2807dc4 100644
--- a/core/lib/Drupal/Core/Condition/ConditionManager.php
+++ b/core/lib/Drupal/Core/Condition/ConditionManager.php
@@ -33,13 +33,13 @@ class ConditionManager extends DefaultPluginManager implements ExecutableManager
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
-    $this->alterInfo($module_handler, 'condition_info');
+    $this->alterInfo('condition_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'condition');
 
     $annotation_namespaces = array(
       'Drupal\Core\Condition\Annotation' => DRUPAL_ROOT . '/core/lib',
     );
-    parent::__construct('Plugin/Condition', $namespaces, $annotation_namespaces, 'Drupal\Core\Condition\Annotation\Condition');
+    parent::__construct('Plugin/Condition', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\Core\Condition\Annotation\Condition');
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Entity/Field/FieldTypePluginManager.php b/core/lib/Drupal/Core/Entity/Field/FieldTypePluginManager.php
index a8c1ef5..be22fc5 100644
--- a/core/lib/Drupal/Core/Entity/Field/FieldTypePluginManager.php
+++ b/core/lib/Drupal/Core/Entity/Field/FieldTypePluginManager.php
@@ -45,8 +45,8 @@ public function __construct(\Traversable $namespaces, CacheBackendInterface $cac
     $annotation_namespaces = array(
       'Drupal\Core\Entity\Annotation' => DRUPAL_ROOT . '/core/lib',
     );
-    parent::__construct('Plugin/field/field_type', $namespaces, $annotation_namespaces, 'Drupal\Core\Entity\Annotation\FieldType');
-    $this->alterInfo($module_handler, 'field_info');
+    parent::__construct('Plugin/field/field_type', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\Core\Entity\Annotation\FieldType');
+    $this->alterInfo('field_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'field_types');
 
     // @todo Remove once all core field types have been converted (see
diff --git a/core/lib/Drupal/Core/Menu/LocalActionManager.php b/core/lib/Drupal/Core/Menu/LocalActionManager.php
index f4aab24..55dc5a7 100644
--- a/core/lib/Drupal/Core/Menu/LocalActionManager.php
+++ b/core/lib/Drupal/Core/Menu/LocalActionManager.php
@@ -59,11 +59,11 @@ class LocalActionManager extends DefaultPluginManager {
    *   The module handler.
    */
   public function __construct(\Traversable $namespaces, ControllerResolverInterface $controller_resolver, Request $request, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Menu/LocalAction', $namespaces, array(), 'Drupal\Core\Annotation\Menu\LocalAction');
+    parent::__construct('Plugin/Menu/LocalAction', $namespaces, $module_handler, array(), 'Drupal\Core\Annotation\Menu\LocalAction');
 
     $this->controllerResolver = $controller_resolver;
     $this->request = $request;
-    $this->alterInfo($module_handler, 'menu_local_actions');
+    $this->alterInfo('menu_local_actions');
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Menu/LocalTaskManager.php b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
index 00837c5..8692672 100644
--- a/core/lib/Drupal/Core/Menu/LocalTaskManager.php
+++ b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
@@ -66,11 +66,11 @@ class LocalTaskManager extends DefaultPluginManager {
    *   The module handler.u
    */
   public function __construct(\Traversable $namespaces, ControllerResolverInterface $controller_resolver, Request $request, RouteProviderInterface $route_provider, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Menu/LocalTask', $namespaces, array(), 'Drupal\Core\Annotation\Menu\LocalTask');
+    parent::__construct('Plugin/Menu/LocalTask', $namespaces, $module_handler, array(), 'Drupal\Core\Annotation\Menu\LocalTask');
     $this->controllerResolver = $controller_resolver;
     $this->request = $request;
     $this->routeProvider = $route_provider;
-    $this->alterInfo($module_handler, 'local_tasks');
+    $this->alterInfo('local_tasks');
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php b/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php
index daddaa7..530f10a 100644
--- a/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php
+++ b/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php
@@ -89,6 +89,8 @@ class DefaultPluginManager extends PluginManagerBase implements PluginManagerInt
    * @param \Traversable $namespaces
    *   An object that implements \Traversable which contains the root paths
    *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
    * @param array $annotation_namespaces
    *   (optional) The namespaces of classes that can be used as annotations.
    *   Defaults to an empty array.
@@ -96,11 +98,12 @@ class DefaultPluginManager extends PluginManagerBase implements PluginManagerInt
    *   (optional) The name of the annotation that contains the plugin definition.
    *   Defaults to 'Drupal\Component\Annotation\Plugin'.
    */
-  public function __construct($subdir, \Traversable $namespaces, $annotation_namespaces = array(), $plugin_definition_annotation_name = 'Drupal\Component\Annotation\Plugin') {
+  public function __construct($subdir, \Traversable $namespaces, ModuleHandlerInterface $module_handler, $annotation_namespaces = array(), $plugin_definition_annotation_name = 'Drupal\Component\Annotation\Plugin') {
     $this->subdir = $subdir;
     $this->discovery = new AnnotatedClassDiscovery($subdir, $namespaces, $annotation_namespaces, $plugin_definition_annotation_name);
     $this->discovery = new ContainerDerivativeDiscoveryDecorator($this->discovery);
     $this->factory = new ContainerFactory($this);
+    $this->moduleHandler = $module_handler;
   }
 
   /**
@@ -127,13 +130,10 @@ public function setCacheBackend(CacheBackendInterface $cache_backend, LanguageMa
   /**
    * Initializes the alter hook.
    *
-   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
-   *   The module handler to invoke the alter hook with.
    * @param string $alter_hook
    *   Name of the alter hook.
    */
-  protected function alterInfo(ModuleHandlerInterface $module_handler, $alter_hook) {
-    $this->moduleHandler = $module_handler;
+  protected function alterInfo($alter_hook) {
     $this->alterHook = $alter_hook;
   }
 
@@ -222,6 +222,12 @@ protected function findDefinitions() {
     if ($this->alterHook) {
       $this->moduleHandler->alter($this->alterHook, $definitions);
     }
+    // If this plugin was provided by a Drupal module, ensure it is enabled.
+    foreach ($definitions as $plugin_id => $plugin_definition) {
+      if (isset($plugin_definition['provider']) && !in_array($plugin_definition['provider'], array('Core', 'Component')) && !$this->moduleHandler->moduleExists($plugin_definition['provider'])) {
+        unset($definitions[$plugin_id]);
+      }
+    }
     return $definitions;
   }
 
diff --git a/core/lib/Drupal/Core/TypedData/TypedDataManager.php b/core/lib/Drupal/Core/TypedData/TypedDataManager.php
index f217fa5..94b6490 100644
--- a/core/lib/Drupal/Core/TypedData/TypedDataManager.php
+++ b/core/lib/Drupal/Core/TypedData/TypedDataManager.php
@@ -46,13 +46,13 @@ class TypedDataManager extends DefaultPluginManager {
   protected $prototypes = array();
 
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
-    $this->alterInfo($module_handler, 'data_type_info');
+    $this->alterInfo('data_type_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'typed_data:types');
 
     $annotation_namespaces = array(
       'Drupal\Core\TypedData\Annotation' => DRUPAL_ROOT . '/core/lib',
     );
-    parent::__construct('Plugin/DataType', $namespaces, $annotation_namespaces, 'Drupal\Core\TypedData\Annotation\DataType');
+    parent::__construct('Plugin/DataType', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\Core\TypedData\Annotation\DataType');
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Validation/ConstraintManager.php b/core/lib/Drupal/Core/Validation/ConstraintManager.php
index 91551bc..50ca9da 100644
--- a/core/lib/Drupal/Core/Validation/ConstraintManager.php
+++ b/core/lib/Drupal/Core/Validation/ConstraintManager.php
@@ -47,9 +47,9 @@ class ConstraintManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Validation/Constraint', $namespaces);
+    parent::__construct('Plugin/Validation/Constraint', $namespaces, $module_handler);
     $this->discovery = new StaticDiscoveryDecorator($this->discovery, array($this, 'registerDefinitions'));
-    $this->alterInfo($module_handler, 'validation_constraint');
+    $this->alterInfo('validation_constraint');
     $this->setCacheBackend($cache_backend, $language_manager, 'validation_constraint');
   }
 
diff --git a/core/modules/block/lib/Drupal/block/Plugin/Type/BlockManager.php b/core/modules/block/lib/Drupal/block/Plugin/Type/BlockManager.php
index 34daaca..165518f 100644
--- a/core/modules/block/lib/Drupal/block/Plugin/Type/BlockManager.php
+++ b/core/modules/block/lib/Drupal/block/Plugin/Type/BlockManager.php
@@ -33,8 +33,8 @@ class BlockManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Block', $namespaces);
-    $this->alterInfo($module_handler, 'block');
+    parent::__construct('Plugin/Block', $namespaces, $module_handler);
+    $this->alterInfo('block');
     $this->setCacheBackend($cache_backend, $language_manager, 'block_plugins');
   }
 }
diff --git a/core/modules/ckeditor/lib/Drupal/ckeditor/CKEditorPluginManager.php b/core/modules/ckeditor/lib/Drupal/ckeditor/CKEditorPluginManager.php
index da2bcfd..3acdec6 100644
--- a/core/modules/ckeditor/lib/Drupal/ckeditor/CKEditorPluginManager.php
+++ b/core/modules/ckeditor/lib/Drupal/ckeditor/CKEditorPluginManager.php
@@ -34,8 +34,8 @@ class CKEditorPluginManager extends DefaultPluginManager {
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
     $annotation_namespaces = array('Drupal\ckeditor\Annotation' => $namespaces['Drupal\ckeditor']);
-    parent::__construct('Plugin/CKEditorPlugin', $namespaces, $annotation_namespaces, 'Drupal\ckeditor\Annotation\CKEditorPlugin');
-    $this->alterInfo($module_handler, 'ckeditor_plugin_info');
+    parent::__construct('Plugin/CKEditorPlugin', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\ckeditor\Annotation\CKEditorPlugin');
+    $this->alterInfo('ckeditor_plugin_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'ckeditor_plugin');
   }
 
diff --git a/core/modules/editor/lib/Drupal/editor/Plugin/EditorManager.php b/core/modules/editor/lib/Drupal/editor/Plugin/EditorManager.php
index 9adf267..5ba8dc6 100644
--- a/core/modules/editor/lib/Drupal/editor/Plugin/EditorManager.php
+++ b/core/modules/editor/lib/Drupal/editor/Plugin/EditorManager.php
@@ -32,8 +32,8 @@ class EditorManager extends DefaultPluginManager {
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
     $annotation_namespaces = array('Drupal\editor\Annotation' => $namespaces['Drupal\editor']);
-    parent::__construct('Plugin/Editor', $namespaces, $annotation_namespaces, 'Drupal\editor\Annotation\Editor');
-    $this->alterInfo($module_handler, 'editor_info');
+    parent::__construct('Plugin/Editor', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\editor\Annotation\Editor');
+    $this->alterInfo('editor_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'editor');
   }
 
diff --git a/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/Type/SelectionPluginManager.php b/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/Type/SelectionPluginManager.php
index 11582f2..77fae43 100644
--- a/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/Type/SelectionPluginManager.php
+++ b/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/Type/SelectionPluginManager.php
@@ -34,7 +34,8 @@ public function __construct(\Traversable $namespaces, CacheBackendInterface $cac
     // method and don't need the derivative discovery decorator.
     $this->factory = new ReflectionFactory($this);
 
-    $this->alterInfo($module_handler, 'entity_reference_selection');
+    $this->moduleHandler = $module_handler;
+    $this->alterInfo('entity_reference_selection');
     $this->setCacheBackend($cache_backend, $language_manager, 'entity_reference_selection');
   }
 
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Type/Formatter/FormatterPluginManager.php b/core/modules/field/lib/Drupal/field/Plugin/Type/Formatter/FormatterPluginManager.php
index 5747fd1..b11b396 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Type/Formatter/FormatterPluginManager.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Type/Formatter/FormatterPluginManager.php
@@ -46,10 +46,10 @@ class FormatterPluginManager extends DefaultPluginManager {
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, LanguageManager $language_manager) {
     $annotation_namespaces = array('Drupal\field\Annotation' => $namespaces['Drupal\field']);
 
-    parent::__construct('Plugin/field/formatter', $namespaces, $annotation_namespaces, 'Drupal\field\Annotation\FieldFormatter');
+    parent::__construct('Plugin/field/formatter', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\field\Annotation\FieldFormatter');
 
     $this->setCacheBackend($cache_backend, $language_manager, 'field_formatter_types');
-    $this->alterInfo($module_handler, 'field_formatter_info');
+    $this->alterInfo('field_formatter_info');
   }
 
   /**
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetPluginManager.php b/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetPluginManager.php
index f8ea9b7..44b4015 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetPluginManager.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetPluginManager.php
@@ -46,10 +46,10 @@ class WidgetPluginManager extends DefaultPluginManager {
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, LanguageManager $language_manager) {
     $annotation_namespaces = array('Drupal\field\Annotation' => $namespaces['Drupal\field']);
 
-    parent::__construct('Plugin/field/widget', $namespaces, $annotation_namespaces, 'Drupal\field\Annotation\FieldWidget');
+    parent::__construct('Plugin/field/widget', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\field\Annotation\FieldWidget');
 
     $this->setCacheBackend($cache_backend, $language_manager, 'field_widget_types');
-    $this->alterInfo($module_handler, 'field_widget_info');
+    $this->alterInfo('field_widget_info');
 
     $this->factory = new WidgetFactory($this);
   }
diff --git a/core/modules/image/lib/Drupal/image/ImageEffectManager.php b/core/modules/image/lib/Drupal/image/ImageEffectManager.php
index 64e251e..06d274e 100644
--- a/core/modules/image/lib/Drupal/image/ImageEffectManager.php
+++ b/core/modules/image/lib/Drupal/image/ImageEffectManager.php
@@ -22,9 +22,9 @@ class ImageEffectManager extends DefaultPluginManager {
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
     $annotation_namespaces = array('Drupal\image\Annotation' => $namespaces['Drupal\image']);
-    parent::__construct('Plugin/ImageEffect', $namespaces, $annotation_namespaces, 'Drupal\image\Annotation\ImageEffect');
+    parent::__construct('Plugin/ImageEffect', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\image\Annotation\ImageEffect');
 
-    $this->alterInfo($module_handler, 'image_effect_info');
+    $this->alterInfo('image_effect_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'image_effect');
   }
 
diff --git a/core/modules/system/lib/Drupal/system/Plugin/ImageToolkitManager.php b/core/modules/system/lib/Drupal/system/Plugin/ImageToolkitManager.php
index f8e334d..08d8980 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/ImageToolkitManager.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/ImageToolkitManager.php
@@ -8,6 +8,7 @@
 namespace Drupal\system\Plugin;
 
 use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Language\LanguageManager;
 use Drupal\Core\Plugin\DefaultPluginManager;
 
@@ -22,13 +23,15 @@ class ImageToolkitManager extends DefaultPluginManager {
    * @param \Traversable $namespaces
    *   An object that implements \Traversable which contains the root paths
    *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
    * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
    *   Cache backend instance to use.
    * @param \Drupal\Core\Language\LanguageManager $language_manager
    *   The language manager.
    */
-  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager) {
-    parent::__construct('Plugin/ImageToolkit', $namespaces);
+  public function __construct(\Traversable $namespaces, ModuleHandlerInterface $module_handler, CacheBackendInterface $cache_backend, LanguageManager $language_manager) {
+    parent::__construct('Plugin/ImageToolkit', $namespaces, $module_handler);
     $this->setCacheBackend($cache_backend, $language_manager, 'image_toolkit');
   }
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/Plugin/PluginTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Plugin/PluginTestBase.php
index c580338..244eaa3 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Plugin/PluginTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Plugin/PluginTestBase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Plugin;
 
+use Drupal\Core\Extension\ModuleHandler;
 use Drupal\simpletest\UnitTestBase;
 use Drupal\plugin_test\Plugin\TestPluginManager;
 use Drupal\plugin_test\Plugin\MockBlockManager;
@@ -36,7 +37,8 @@ public function setUp() {
     //   as derivatives and ReflectionFactory.
     $this->testPluginManager = new TestPluginManager();
     $this->mockBlockManager = new MockBlockManager();
-    $this->defaultsTestPluginManager = new DefaultsTestPluginManager();
+    $module_handler = new ModuleHandler();
+    $this->defaultsTestPluginManager = new DefaultsTestPluginManager($module_handler);
 
     // The expected plugin definitions within each manager. Several tests assert
     // that these plugins and their definitions are found and returned by the
diff --git a/core/modules/system/tests/modules/plugin_test/lib/Drupal/plugin_test/Plugin/DefaultsTestPluginManager.php b/core/modules/system/tests/modules/plugin_test/lib/Drupal/plugin_test/Plugin/DefaultsTestPluginManager.php
index 8ca3165..fb8f897 100644
--- a/core/modules/system/tests/modules/plugin_test/lib/Drupal/plugin_test/Plugin/DefaultsTestPluginManager.php
+++ b/core/modules/system/tests/modules/plugin_test/lib/Drupal/plugin_test/Plugin/DefaultsTestPluginManager.php
@@ -9,6 +9,7 @@
 
 use Drupal\Component\Plugin\Discovery\StaticDiscovery;
 use Drupal\Component\Plugin\Factory\DefaultFactory;
+use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\DefaultPluginManager;
 
 /**
@@ -16,13 +17,20 @@
  */
 class DefaultsTestPluginManager extends DefaultPluginManager {
 
-  public function __construct() {
+  /**
+   * Constructs a new DefaultsTestPluginManager instance.
+   *
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
+   */
+  public function __construct(ModuleHandlerInterface $module_handler) {
     // Create the object that can be used to return definitions for all the
     // plugins available for this type. Most real plugin managers use a richer
     // discovery implementation, but StaticDiscovery lets us add some simple
     // mock plugins for unit testing.
     $this->discovery = new StaticDiscovery();
     $this->factory = new DefaultFactory($this);
+    $this->moduleHandler = $module_handler;
 
     // Specify default values.
     $this->defaults = array(
diff --git a/core/modules/tour/lib/Drupal/tour/TipPluginManager.php b/core/modules/tour/lib/Drupal/tour/TipPluginManager.php
index fb18d3b..bc7cffc 100644
--- a/core/modules/tour/lib/Drupal/tour/TipPluginManager.php
+++ b/core/modules/tour/lib/Drupal/tour/TipPluginManager.php
@@ -32,9 +32,9 @@ class TipPluginManager extends DefaultPluginManager {
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, LanguageManager $language_manager, ModuleHandlerInterface $module_handler) {
     $annotation_namespaces = array('Drupal\tour\Annotation' => $namespaces['Drupal\tour']);
-    parent::__construct('Plugin/tour/tip', $namespaces, $annotation_namespaces, 'Drupal\tour\Annotation\Tip');
+    parent::__construct('Plugin/tour/tip', $namespaces, $module_handler, $annotation_namespaces, 'Drupal\tour\Annotation\Tip');
 
-    $this->alterInfo($module_handler, 'tour_tips_info');
+    $this->alterInfo('tour_tips_info');
     $this->setCacheBackend($cache_backend, $language_manager, 'tour');
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Extension/ModuleHandlerUnitTest.php b/core/tests/Drupal/Tests/Core/Extension/ModuleHandlerUnitTest.php
index 45ad0d2..de471ef 100644
--- a/core/tests/Drupal/Tests/Core/Extension/ModuleHandlerUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Extension/ModuleHandlerUnitTest.php
@@ -7,10 +7,6 @@
 
 namespace Drupal\Tests\Core\Extension;
 
-if (!defined('DRUPAL_ROOT')) {
-  define('DRUPAL_ROOT', dirname(dirname(substr(__DIR__, 0, -strlen(__NAMESPACE__)))));
-}
-
 use Drupal\Core\Extension\ModuleHandler;
 use Drupal\Tests\UnitTestCase;
 
diff --git a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
index bd6ba26..d1327ad 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
@@ -77,6 +77,31 @@ public function testDefaultPluginManager() {
   }
 
   /**
+   * Tests the plugin manager with a disabled module.
+   */
+  public function testDefaultPluginManagerWithDisabledModule() {
+    $definitions = $this->expectedDefinitions;
+    $definitions['cherry'] = array(
+      'id' => 'cherry',
+      'label' => 'Cherry',
+      'color' => 'red',
+      'class' => 'Drupal\plugin_test\Plugin\plugin_test\fruit\Cherry',
+      'provider' => 'disabled_module',
+    );
+
+    $module_handler = $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface');
+
+    $module_handler->expects($this->once())
+      ->method('moduleExists')
+      ->with('disabled_module')
+      ->will($this->returnValue(FALSE));
+
+    $plugin_manager = new TestPluginManager($this->namespaces, $definitions, $module_handler, 'test_alter_hook');
+
+    $this->assertEmpty($plugin_manager->getDefinition('cherry'), 'Plugin information of a disabled module still available');
+  }
+
+  /**
    * Tests the plugin manager with no cache and altering.
    */
   public function testDefaultPluginManagerWithAlter() {
@@ -157,3 +182,7 @@ public function testDefaultPluginManagerWithFilledCache() {
   }
 
 }
+
+if (!defined('DRUPAL_ROOT')) {
+  define('DRUPAL_ROOT', dirname(dirname(substr(__DIR__, 0, -strlen(__NAMESPACE__)))));
+}
diff --git a/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php b/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
index e88008e..a7ea79d 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/TestPluginManager.php
@@ -41,8 +41,10 @@ public function __construct(\Traversable $namespaces, array $definitions, Module
       $this->discovery->setDefinition($key, $definition);
     }
 
-    if ($module_handler && $alter_hook) {
-      $this->alterInfo($module_handler, $alter_hook);
+    $this->moduleHandler = $module_handler;
+
+    if ($alter_hook) {
+      $this->alterInfo($alter_hook);
     }
   }