class MediaSelection

class MediaSelection extends DefaultSelection {
  
  /**
   * {@inheritdoc}
   */
  protected function buildEntityQuery($match = NULL, $match_operator = 'CONTAINS') {
    $query = parent::buildEntityQuery($match, $match_operator);
    // Ensure that users with insufficient permission cannot see unpublished
    // entities.
    if (!$this->currentUser
      ->hasPermission('administer media')) {
      $query->condition('status', 1);
    }
    return $query;
  }
  
  /**
   * {@inheritdoc}
   */
  public function createNewEntity($entity_type_id, $bundle, $label, $uid) {
    $media = parent::createNewEntity($entity_type_id, $bundle, $label, $uid);
    // In order to create a referenceable media, it needs to published.
    /** @var \Drupal\media\MediaInterface $media */
    $media->setPublished();
    return $media;
  }
  
  /**
   * {@inheritdoc}
   */
  public function validateReferenceableNewEntities(array $entities) {
    $entities = parent::validateReferenceableNewEntities($entities);
    // Mirror the conditions checked in buildEntityQuery().
    if (!$this->currentUser
      ->hasPermission('administer media')) {
      $entities = array_filter($entities, function ($media) {
        /** @var \Drupal\media\MediaInterface $media */
        return $media->isPublished();
      });
    }
    return $entities;
  }

}