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chromium/third_party/blink/web_tests/external/wpt/html/browsers/the-window-object/support/noopener-target.html 

<!DOCTYPE html>
<script>
  var channelName = location.search.substr(1);
  var channel = new BroadcastChannel(channelName);
  channel.postMessage({ name: window.name,
                        haveOpener: window.opener !== null });

  // Because messages are not delivered synchronously and because closing a
  // browsing context prompts the eventual clearing of all task sources, this
  // document should not be closed until the opener document has confirmed
  // receipt.
  channel.onmessage = function() {
    window.close();
  };
</script>