--- /dev/null
+<?php
+
+namespace Drupal\media;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\DefaultPluginManager;
+use Drupal\media\Annotation\MediaSource;
+
+/**
+ * Manages media source plugins.
+ */
+class MediaSourceManager extends DefaultPluginManager {
+
+ /**
+ * Constructs a new MediaSourceManager.
+ *
+ * @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, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+ parent::__construct('Plugin/media/Source', $namespaces, $module_handler, MediaSourceInterface::class, MediaSource::class);
+
+ $this->alterInfo('media_source_info');
+ $this->setCacheBackend($cache_backend, 'media_source_plugins');
+ }
+
+}