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chromium/third_party/blink/web_tests/http/tests/media/autoplay/resources/webaudio-iframe-no-gesture.html 

<!DOCTYPE html>
<html>
<body>
<script>
// Make sure this overrides any preset autoplay policy.
internals.settings.setAutoplayPolicy('document-user-activation-required');
internals.settings.autoplayIgnoresWebAudioEnabled = false;

let result = 'failed';

try {
  const ac = new AudioContext();
  result = ac.state;
} catch (e) {
  result = 'creation_failed';
}

top.postMessage(result, '*');
</script>