LayoutBundle.php

<?php

/**
 * @file
 * Definition of Drupal\layout\LayoutBundle.
 */
namespace Drupal\Layout;

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Bundle\Bundle;

/**
 * Layout dependency injection container.
 */
class LayoutBundle extends Bundle {

  /**
   * Overrides Symfony\Component\HttpKernel\Bundle\Bundle::build().
   */
  public function build(ContainerBuilder $container) {

    // Register the LayoutManager class with the dependency injection container.
    $container
      ->register('plugin.manager.layout', 'Drupal\\layout\\Plugin\\Type\\LayoutManager');
  }

}