magento2/app/code/Magento/Sales/Controller/Adminhtml/Order/CommentsHistory.php

<?php
/**
 *
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Sales\Controller\Adminhtml\Order;

use Magento\Framework\App\Action\HttpGetActionInterface;
use Magento\Backend\App\Action;
use Magento\Framework\App\Action\HttpPostActionInterface;
use Magento\Sales\Api\OrderManagementInterface;
use Magento\Sales\Api\OrderRepositoryInterface;
use Psr\Log\LoggerInterface;
use Magento\Sales\Controller\Adminhtml\Order as OrderAction;

/**
 * Comments History tab, needs to be accessible by POST because of tabs mechanism.
 *
 * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
 */
class CommentsHistory extends OrderAction implements HttpGetActionInterface, HttpPostActionInterface
{
    /**
     * @var \Magento\Framework\View\LayoutFactory
     */
    protected $layoutFactory;

    /**
     * @param Action\Context $context
     * @param \Magento\Framework\Registry $coreRegistry
     * @param \Magento\Framework\App\Response\Http\FileFactory $fileFactory
     * @param \Magento\Framework\Translate\InlineInterface $translateInline
     * @param \Magento\Framework\View\Result\PageFactory $resultPageFactory
     * @param \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory
     * @param \Magento\Framework\View\Result\LayoutFactory $resultLayoutFactory
     * @param \Magento\Framework\Controller\Result\RawFactory $resultRawFactory
     * @param OrderManagementInterface $orderManagement
     * @param OrderRepositoryInterface $orderRepository
     * @param LoggerInterface $logger
     * @param \Magento\Framework\View\LayoutFactory $layoutFactory
     *
     * @SuppressWarnings(PHPMD.ExcessiveParameterList)
     * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
     */
    public function __construct(
        Action\Context $context,
        \Magento\Framework\Registry $coreRegistry,
        \Magento\Framework\App\Response\Http\FileFactory $fileFactory,
        \Magento\Framework\Translate\InlineInterface $translateInline,
        \Magento\Framework\View\Result\PageFactory $resultPageFactory,
        \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory,
        \Magento\Framework\View\Result\LayoutFactory $resultLayoutFactory,
        \Magento\Framework\Controller\Result\RawFactory $resultRawFactory,
        OrderManagementInterface $orderManagement,
        OrderRepositoryInterface $orderRepository,
        LoggerInterface $logger,
        \Magento\Framework\View\LayoutFactory $layoutFactory
    ) {
        $this->layoutFactory = $layoutFactory;
        parent::__construct(
            $context,
            $coreRegistry,
            $fileFactory,
            $translateInline,
            $resultPageFactory,
            $resultJsonFactory,
            $resultLayoutFactory,
            $resultRawFactory,
            $orderManagement,
            $orderRepository,
            $logger
        );
    }

    /**
     * Generate order history for ajax request
     *
     * @return \Magento\Framework\Controller\Result\Raw
     */
    public function execute()
    {
        $this->_initOrder();
        $layout = $this->layoutFactory->create();
        $html = $layout->createBlock(\Magento\Sales\Block\Adminhtml\Order\View\Tab\History::class)
            ->toHtml();
        $this->_translateInline->processResponseBody($html);
        /** @var \Magento\Framework\Controller\Result\Raw $resultRaw */
        $resultRaw = $this->resultRawFactory->create();
        $resultRaw->setContents($html);
        return $resultRaw;
    }
}