LayoutTests/http/tests/from-origin/resources/fetch.php

<?php
if($_GET["fromOrigin"] == "same") {
    header("From-Origin: Same");
} elseif($_GET["fromOrigin"] == "same-site") {
    header("From-Origin: Same-Site");
}

if (isset($_SERVER['HTTP_ORIGIN'])) {
    header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
}
$data = '{
	"Fetch": true
}';
echo json_encode($data);
?>