diff --git a/core/core.services.yml b/core/core.services.yml
index b97f115..d04bcc6 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -150,7 +150,7 @@ services:
     arguments: ['@typed_data_manager']
   cron:
     class: Drupal\Core\Cron
-    arguments: ['@module_handler', '@lock', '@queue', '@state', '@current_user', '@session_manager', '@logger.channel.cron']
+    arguments: ['@module_handler', '@lock', '@queue', '@state', '@current_user', '@session_manager', '@logger.channel.cron', '@plugin.manager.queue']
   diff.formatter:
     class: Drupal\Core\Diff\DiffFormatter
     arguments: ['@config.factory']
@@ -346,9 +346,9 @@ services:
   plugin.manager.display_variant:
     class: Drupal\Core\Display\VariantManager
     parent: default_plugin_manager
-  plugin.manager.queue.item:
+  plugin.manager.queue:
     class: Drupal\Core\Queue\QueuePluginManager
-    arguments: ['@container.namespaces', '@module_handler']
+    parent: default_plugin_manager
   plugin.cache_clearer:
     class: Drupal\Core\Plugin\CachedDiscoveryClearer
   paramconverter.menu_link:
diff --git a/core/lib/Drupal/Core/Annotation/QueuePlugin.php b/core/lib/Drupal/Core/Annotation/QueuePlugin.php
index c30bf2d..5366b51 100644
--- a/core/lib/Drupal/Core/Annotation/QueuePlugin.php
+++ b/core/lib/Drupal/Core/Annotation/QueuePlugin.php
@@ -26,7 +26,7 @@
  * @see hook_cron()
  * @see hook_queue_info_alter()
  * @see \Drupal\Core\Queue\QueuePluginInterface
- * @see \Drupal\Core\Queue\QueuePluginManager
+ * @see \Drupal\Core\Queue\QueuePluginManagerInterface
  *
  * @Annotation
  */
diff --git a/core/lib/Drupal/Core/Cron.php b/core/lib/Drupal/Core/Cron.php
index cbb1a9c..8bfe378 100644
--- a/core/lib/Drupal/Core/Cron.php
+++ b/core/lib/Drupal/Core/Cron.php
@@ -8,6 +8,7 @@
 namespace Drupal\Core;
 
 use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Queue\QueuePluginManagerInterface;
 use Drupal\Core\State\StateInterface;
 use Drupal\Core\Lock\LockBackendInterface;
 use Drupal\Core\Queue\QueueFactory;
@@ -72,6 +73,13 @@ class Cron implements CronInterface {
   protected $logger;
 
   /**
+   * The queue plugin manager.
+   *
+   * @var \Drupal\Core\Queue\QueuePluginManagerInterface
+   */
+  protected $queueManager;
+
+  /**
    * Constructs a cron object.
    *
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
@@ -88,8 +96,10 @@ class Cron implements CronInterface {
    *   The session manager.
    * @param \Psr\Log\LoggerInterface $logger
    *   A logger instance.
+   * @param \Drupal\Core\Queue\QueuePluginManagerInterface
+   *   The queue plugin manager.
    */
-  public function __construct(ModuleHandlerInterface $module_handler, LockBackendInterface $lock, QueueFactory $queue_factory, StateInterface $state, AccountProxyInterface $current_user, SessionManagerInterface $session_manager, LoggerInterface $logger) {
+  public function __construct(ModuleHandlerInterface $module_handler, LockBackendInterface $lock, QueueFactory $queue_factory, StateInterface $state, AccountProxyInterface $current_user, SessionManagerInterface $session_manager, LoggerInterface $logger, QueuePluginManagerInterface $queue_manager) {
     $this->moduleHandler = $module_handler;
     $this->lock = $lock;
     $this->queueFactory = $queue_factory;
@@ -97,6 +107,7 @@ public function __construct(ModuleHandlerInterface $module_handler, LockBackendI
     $this->currentUser = $current_user;
     $this->sessionManager = $session_manager;
     $this->logger = $logger;
+    $this->queueManager = $queue_manager;
   }
 
   /**
@@ -162,16 +173,13 @@ protected function setCronLastTime() {
    */
   protected function processQueues() {
     // Grab the defined cron queues.
-    $manager = \Drupal::service('plugin.manager.queue.item');
-    $queues = $manager->getDefinitions();
-
-    foreach ($queues as $queue_name => $info) {
+    foreach ($this->queueManager->getDefinitions() as $queue_name => $info) {
       if (isset($info['cron'])) {
         // Make sure every queue exists. There is no harm in trying to recreate
         // an existing queue.
         $this->queueFactory->get($queue_name)->createQueue();
 
-        $queue_item = $manager->createInstance($queue_name);
+        $queue_item = $this->queueManager->createInstance($queue_name);
         $end = time() + (isset($info['cron']['time']) ? $info['cron']['time'] : 15);
         $queue = $this->queueFactory->get($queue_name);
         while (time() < $end && ($item = $queue->claimItem())) {
diff --git a/core/lib/Drupal/Core/Queue/QueueFactory.php b/core/lib/Drupal/Core/Queue/QueueFactory.php
index 6dce837..70824c3 100644
--- a/core/lib/Drupal/Core/Queue/QueueFactory.php
+++ b/core/lib/Drupal/Core/Queue/QueueFactory.php
@@ -50,7 +50,7 @@ function __construct(Settings $settings) {
    *   least once is important, FALSE if scalability is the main concern. Defaults
    *   to FALSE.
    *
-   * @return \Drupal\Core\QueueStore\QueueInterface
+   * @return \Drupal\Core\Queue\QueueInterface
    *   A queue implementation for the given name.
    */
   public function get($name, $reliable = FALSE) {
diff --git a/core/lib/Drupal/Core/Queue/QueuePluginBase.php b/core/lib/Drupal/Core/Queue/QueuePluginBase.php
index 04a8288..87fa4cd 100644
--- a/core/lib/Drupal/Core/Queue/QueuePluginBase.php
+++ b/core/lib/Drupal/Core/Queue/QueuePluginBase.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains Drupal\Core\Queue\QueuePluginBase.
+ * Contains \Drupal\Core\Queue\QueuePluginBase.
  */
 
 namespace Drupal\Core\Queue;
diff --git a/core/lib/Drupal/Core/Queue/QueuePluginInterface.php b/core/lib/Drupal/Core/Queue/QueuePluginInterface.php
index 4914270..bada537 100644
--- a/core/lib/Drupal/Core/Queue/QueuePluginInterface.php
+++ b/core/lib/Drupal/Core/Queue/QueuePluginInterface.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains Drupal\Core\Queue\QueuePluginInterface.
+ * Contains \Drupal\Core\Queue\QueuePluginInterface.
  */
 
 namespace Drupal\Core\Queue;
diff --git a/core/lib/Drupal/Core/Queue/QueuePluginManager.php b/core/lib/Drupal/Core/Queue/QueuePluginManager.php
index e79fdae..3253422 100644
--- a/core/lib/Drupal/Core/Queue/QueuePluginManager.php
+++ b/core/lib/Drupal/Core/Queue/QueuePluginManager.php
@@ -7,13 +7,14 @@
 
 namespace Drupal\Core\Queue;
 
+use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\DefaultPluginManager;
 
 /**
  * Defines the queue item manager.
  */
-class QueuePluginManager extends DefaultPluginManager {
+class QueuePluginManager extends DefaultPluginManager implements QueuePluginManagerInterface {
 
   /**
    * Constructs an QueuePluginManager object.
@@ -21,12 +22,16 @@ class QueuePluginManager 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\Cache\CacheBackendInterface $cache_backend
+   *   Cache backend instance to use.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *   The module handler.
    */
-  public function __construct(\Traversable $namespaces, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/QueuePlugin', $namespaces, 'Drupal\Core\Annotation\QueuePlugin');
-    $this->alterInfo($module_handler, 'queue_info');
+  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+    parent::__construct('Plugin/QueuePlugin', $namespaces, $module_handler, 'Drupal\Core\Queue\QueuePluginInterface', 'Drupal\Core\Annotation\QueuePlugin');
+
+    $this->setCacheBackend($cache_backend, 'queue_plugins');
+    $this->alterInfo('queue_info');
   }
 
   /**
@@ -37,10 +42,19 @@ public function processDefinition(&$definition, $plugin_id) {
 
     // Assign a default time if a cron is specified.
     if (isset($definition['cron'])) {
-      $definition['cron'] += array(
+      $definition['cron'] += [
         'time' => 15,
-      );
+      ];
     }
   }
 
+  /**
+   * {@inheritdoc}
+   *
+   * @return \Drupal\Core\Queue\QueuePluginInterface
+   */
+  public function createInstance($plugin_id, array $configuration = []) {
+    return parent::createInstance($plugin_id, $configuration);
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Queue/QueuePluginManagerInterface.php b/core/lib/Drupal/Core/Queue/QueuePluginManagerInterface.php
new file mode 100644
index 0000000..8fdd555
--- /dev/null
+++ b/core/lib/Drupal/Core/Queue/QueuePluginManagerInterface.php
@@ -0,0 +1,17 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Queue\QueuePluginManagerInterface.
+ */
+
+namespace Drupal\Core\Queue;
+
+use Drupal\Component\Plugin\PluginManagerInterface;
+
+/**
+ * Provides an interface for a queue item manager.
+ */
+interface QueuePluginManagerInterface extends PluginManagerInterface {
+
+}
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/QueuePlugin/AggregatorRefresh.php b/core/modules/aggregator/src/Plugin/QueuePlugin/AggregatorRefresh.php
similarity index 70%
rename from core/modules/aggregator/lib/Drupal/aggregator/Plugin/QueuePlugin/AggregatorRefresh.php
rename to core/modules/aggregator/src/Plugin/QueuePlugin/AggregatorRefresh.php
index 3523ef9..0f7a745 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/QueuePlugin/AggregatorRefresh.php
+++ b/core/modules/aggregator/src/Plugin/QueuePlugin/AggregatorRefresh.php
@@ -7,8 +7,7 @@
 
 namespace Drupal\aggregator\Plugin\QueuePlugin;
 
-use Drupal\Core\Annotation\QueuePlugin;
-use Drupal\Core\Annotation\Translation;
+use Drupal\aggregator\FeedInterface;
 use Drupal\Core\Queue\QueuePluginBase;
 
 /**
@@ -24,8 +23,9 @@ class AggregatorRefresh extends QueuePluginBase {
    * {@inheritdoc}
    */
   public function processItem($data) {
-    // @todo Convert once aggregator_refresh() is converted to a service.
-    aggregator_refresh($data);
+    if ($data instanceof FeedInterface) {
+      $data->refreshItems();
+    }
   }
 
 }
diff --git a/core/modules/aggregator/src/Tests/AggregatorCronTest.php b/core/modules/aggregator/src/Tests/AggregatorCronTest.php
index 8a8ee7d..59b6386 100644
--- a/core/modules/aggregator/src/Tests/AggregatorCronTest.php
+++ b/core/modules/aggregator/src/Tests/AggregatorCronTest.php
@@ -21,11 +21,11 @@ public function testCron() {
     $this->createSampleNodes();
     $feed = $this->createFeed();
     $this->cronRun();
-    $this->assertEqual(5, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField(), 'Expected number of items in database.');
+    $this->assertEqual(5, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField());
     $this->deleteFeedItems($feed);
-    $this->assertEqual(0, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField(), 'Expected number of items in database.');
+    $this->assertEqual(0, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField());
     $this->cronRun();
-    $this->assertEqual(5, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField(), 'Expected number of items in database.');
+    $this->assertEqual(5, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField());
 
     // Test feed locking when queued for update.
     $this->deleteFeedItems($feed);
@@ -36,7 +36,7 @@ public function testCron() {
       ))
       ->execute();
     $this->cronRun();
-    $this->assertEqual(0, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField(), 'Expected number of items in database.');
+    $this->assertEqual(0, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField());
     db_update('aggregator_feed')
       ->condition('fid', $feed->id())
       ->fields(array(
@@ -44,6 +44,6 @@ public function testCron() {
       ))
       ->execute();
     $this->cronRun();
-    $this->assertEqual(5, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField(), 'Expected number of items in database.');
+    $this->assertEqual(5, db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField());
   }
 }
diff --git a/core/modules/locale/lib/Drupal/locale/Plugin/QueuePlugin/LocaleTranslation.php b/core/modules/locale/src/Plugin/QueuePlugin/LocaleTranslation.php
similarity index 91%
rename from core/modules/locale/lib/Drupal/locale/Plugin/QueuePlugin/LocaleTranslation.php
rename to core/modules/locale/src/Plugin/QueuePlugin/LocaleTranslation.php
index 0a52ece..6ecb715 100644
--- a/core/modules/locale/lib/Drupal/locale/Plugin/QueuePlugin/LocaleTranslation.php
+++ b/core/modules/locale/src/Plugin/QueuePlugin/LocaleTranslation.php
@@ -7,8 +7,6 @@
 
 namespace Drupal\locale\Plugin\QueuePlugin;
 
-use Drupal\Core\Annotation\QueuePlugin;
-use Drupal\Core\Annotation\Translation;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\Core\Queue\QueueInterface;
@@ -62,7 +60,7 @@ public function __construct(array $configuration, $plugin_id, array $plugin_defi
   /**
    * {@inheritdoc}
    */
-  public static function create(ContainerInterface $container, array $configuration, $plugin_id, array $plugin_definition) {
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
     return new static(
       $configuration,
       $plugin_id,
@@ -95,18 +93,18 @@ public function processItem($data) {
     // through via the queue and is part of the $data.
     $last = count($args) - 1;
     if (!is_array($args[$last]) || !isset($args[$last]['finished'])) {
-      $batch_context = array(
-        'sandbox'  => array(),
-        'results'  => array(),
+      $batch_context = [
+        'sandbox'  => [],
+        'results'  => [],
         'finished' => 1,
         'message'  => '',
-      );
+      ];
     }
     else {
       $batch_context = $args[$last];
       unset ($args[$last]);
     }
-    $args = array_merge($args, array(&$batch_context));
+    $args = array_merge($args, [&$batch_context]);
 
     // Call the batch operation function.
     call_user_func_array($function, $args);
@@ -115,7 +113,7 @@ public function processItem($data) {
     // continue the task. This is typically the translation import task.
     if ($batch_context['finished'] < 1) {
       unset($batch_context['strings']);
-      $this->queue->createItem(array($function, $args));
+      $this->queue->createItem([$function, $args]);
     }
   }
 
diff --git a/core/modules/system/system.api.php b/core/modules/system/system.api.php
index 932a143..0c3dbb8 100644
--- a/core/modules/system/system.api.php
+++ b/core/modules/system/system.api.php
@@ -118,35 +118,6 @@ function hook_queue_info_alter(&$queues) {
 }
 
 /**
- * Work on a single queue item.
- *
- * Callback for hook_queue_info().
- *
- * @param $queue_item_data
- *   The data that was passed to \Drupal\Core\Queue\QueueInterface::createItem()
- *   when the item was queued.
- *
- * @throws \Exception
- *   The worker callback may throw an exception to indicate there was a problem.
- *   The cron process will log the exception, and leave the item in the queue to
- *   be processed again later.
- * @throws \Drupal\Core\Queue\SuspendQueueException
- *   More specifically, a SuspendQueueException should be thrown when the
- *   callback is aware that the problem will affect all subsequent workers of
- *   its queue. For example, a callback that makes HTTP requests may find that
- *   the remote server is not responding. The cron process will behave as with a
- *   normal Exception, and in addition will not attempt to process further items
- *   from the current item's queue during the current cron run.
- *
- * @see \Drupal\Core\Cron::run()
- */
-function callback_queue_worker($queue_item_data) {
-  $node = node_load($queue_item_data);
-  $node->title = 'Updated title';
-  $node->save();
-}
-
-/**
  * Allows modules to declare their own Form API element types and specify their
  * default values.
  *
diff --git a/core/modules/system/tests/modules/cron_queue_test/cron_queue_test.module b/core/modules/system/tests/modules/cron_queue_test/cron_queue_test.module
deleted file mode 100644
index c46fdb9..0000000
--- a/core/modules/system/tests/modules/cron_queue_test/cron_queue_test.module
+++ /dev/null
@@ -1,38 +0,0 @@
-<?php
-
-function cron_queue_test_queue_info() {
-  $queues['cron_queue_test_exception'] = array(
-    'title' => t('Exception test'),
-    'worker callback' => 'cron_queue_test_exception',
-    // Only needed if this queue should be processed by cron.
-    'cron' => array(
-      'time' => 60,
-    ),
-  );
-  $queues['cron_queue_test_broken_queue'] = array(
-    'title' => t('Broken queue test'),
-    'worker callback' => 'cron_queue_test_broken_queue',
-    // Only needed if this queue should be processed by cron.
-    'cron' => array(
-      'time' => 60,
-    ),
-  );
-
-  return $queues;
-}
-
-function cron_queue_test_exception($item) {
-  throw new Exception('That is not supposed to happen.');
-}
-
-/**
- * Implements callback_queue_worker().
- *
- * This queue is declared broken if the queue item data is 'crash'.
- */
-function cron_queue_test_broken_queue($queue_item_data) {
-  if ($queue_item_data == 'crash') {
-    throw new \Drupal\Core\Queue\SuspendQueueException('The queue is broken.');
-  }
-  // Do nothing otherwise.
-}
diff --git a/core/modules/system/tests/modules/cron_queue_test/src/Plugin/QueuePlugin/CronQueueTestBrokenQueue.php b/core/modules/system/tests/modules/cron_queue_test/src/Plugin/QueuePlugin/CronQueueTestBrokenQueue.php
new file mode 100644
index 0000000..b70f7b6
--- /dev/null
+++ b/core/modules/system/tests/modules/cron_queue_test/src/Plugin/QueuePlugin/CronQueueTestBrokenQueue.php
@@ -0,0 +1,32 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\cron_queue_test\Plugin\QueuePlugin\CronQueueTestBrokenQueue.
+ */
+
+namespace Drupal\cron_queue_test\Plugin\QueuePlugin;
+
+use Drupal\Core\Queue\QueuePluginBase;
+use Drupal\Core\Queue\SuspendQueueException;
+
+/**
+ * @QueuePlugin(
+ *   id = "cron_queue_test_broken_queue",
+ *   title = @Translation("Broken queue test"),
+ *   cron = {"time" = 60}
+ * )
+ */
+class CronQueueTestBrokenQueue extends QueuePluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processItem($data) {
+    if ($data == 'crash') {
+      throw new SuspendQueueException('The queue is broken.');
+    }
+    // Do nothing otherwise.
+  }
+
+}
diff --git a/core/modules/system/tests/modules/cron_queue_test/src/Plugin/QueuePlugin/CronQueueTestException.php b/core/modules/system/tests/modules/cron_queue_test/src/Plugin/QueuePlugin/CronQueueTestException.php
new file mode 100644
index 0000000..d159c67
--- /dev/null
+++ b/core/modules/system/tests/modules/cron_queue_test/src/Plugin/QueuePlugin/CronQueueTestException.php
@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\cron_queue_test\Plugin\QueuePlugin\CronQueueTestException.
+ */
+
+namespace Drupal\cron_queue_test\Plugin\QueuePlugin;
+
+use Drupal\Core\Queue\QueuePluginBase;
+
+/**
+ * @QueuePlugin(
+ *   id = "cron_queue_test_exception",
+ *   title = @Translation("Exception test"),
+ *   cron = {"time" = 60}
+ * )
+ */
+class CronQueueTestException extends QueuePluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processItem($data) {
+    throw new \Exception('That is not supposed to happen.');
+  }
+
+}