Display restricted PDFs inline in the browser

my_pmpro_inline_restricted_pdfs.php

<?php
/**
 * Display restricted PDFs inline in the browser for members with access.
 *
 * Restrict files: https://www.paidmembershipspro.com/locking-down-protecting-files-with-pmpro/
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_inline_restricted_pdfs( $content_disposition, $file, $file_dir, $file_path ) {
	$finfo     = finfo_open( FILEINFO_MIME_TYPE );
	$mime_type = finfo_file( $finfo, $file_path );
	finfo_close( $finfo );

	if ( 'application/pdf' === $mime_type ) {
		return 'inline';
	}

	return $content_disposition;
}
add_filter( 'pmpro_restricted_file_content_disposition', 'my_pmpro_inline_restricted_pdfs', 10, 4 );