chromium/src/third_party/blink/web_tests/http/tests/xmlhttprequest/resources/post-echo.php

<?php
header('Access-Control-Allow-Origin: *');
if (isset($_POST['type']))
    header("Content-Type: {$_POST['type']}");
else
    header("Content-Type: text/plain");

$str = @file_get_contents('php://input');
header("Content-Length: " . strlen($str));
echo $str;
?>