BackButton.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Theme\Block\Adminhtml\Design\Config\Edit;

use Magento\Backend\Block\Widget\Context;
use Magento\Framework\UrlInterface;
use Magento\Framework\View\Element\UiComponent\Control\ButtonProviderInterface;

/**
 * "Back" button data provider
 *
 * @api
 * @since 100.1.0
 */
class BackButton implements ButtonProviderInterface
{
    /**
     * Url Builder
     *
     * @var UrlInterface
     * @since 100.1.0
     */
    protected $urlBuilder;

    /**
     * @param Context $context
     */
    public function __construct(
        Context $context
    ) {
        $this->urlBuilder = $context->getUrlBuilder();
    }

    /**
     * @inheritdoc
     * @since 100.1.0
     */
    public function getButtonData()
    {
        return [
            'label' => __('Back'),
            'on_click' => sprintf("location.href = '%s';", $this->getBackUrl()),
            'class' => 'back',
            'sort_order' => 10
        ];
    }

    /**
     * Get URL for back (reset) button
     *
     * @return string
     * @since 100.1.0
     */
    public function getBackUrl()
    {
        return $this->urlBuilder->getUrl('*/*/');
    }
}