chromium/third_party/blink/web_tests/mhtml/cid_in_html_resource.html

<head>
  <script>
    if (window.testRunner)
      testRunner.dumpAsText();
  </script>
  <link rel="stylesheet" type="text/css" href="cid:xxxxxx">
  <style type="text/css">
    @font-face {
      font-family: "My Custom Font";
      src: url(cid:xxxxxx) format("truetype");
    }
    body { 
      font-family: "My Custom Font", Verdana, Tahoma;
    }
  </style>
</head>
<body>
  <script src="cid:xxxxxx"></script>
  <img href="cid:xxxxxx"></img>
  <p>
    No Content-ID url are expected outside of an MHTML document.
    The document should load without crashing.
  </p>
</body>