{channel_name}");
bc3.postMessage("from-${iframe_name}");
</script>`;

promise_test(t => {
  return new Promise((resolve, reject) => {
    const channel_name = "opaque-origin-test-2";
    const bc1 = new BroadcastChannel(channel_name);
    bc1.onmessage = t.unreached_func("Received message from an opaque origin");

    // We'll create an iframe and have it send a BroadcastChannel message
    // between two instances. Once the message is received, it will postMessage
    // back and we'll repeat this with an