Media Library: show only own media

/**
 * Implements hook_views_query_alter().
 */
function mymodule_views_query_alter(ViewExecutable $view, QueryPluginBase $query) {
  if ($view->id() === 'media_library') {
    $user = \Drupal::currentUser();
    $user_roles = $user->getRoles();

    // Check if the user has "View all media" permission.
    if (in_array('administrator', $user_roles, TRUE) || $user->hasPermission('View all media')) {
      return;
    }

    $query->addWhereExpression('AND', 'media_field_data.uid = :current_user_id', [':current_user_id' => $user->id()]);
  }
}