chromium/third_party/blink/web_tests/media/controls/volumechange-muted-attribute.html

<!DOCTYPE html>
<html>
<title>This tests that controls are properly updated when muted content attribute is changed.</title>
<script src="../media-controls.js"></script>
<audio preload="auto" controls muted></audio>
<video preload="auto" controls muted></video>
<script>
  var audio = document.querySelector('audio');
  enableTestMode(audio);
  audio.src = '../content/test.oga';

  var video = document.querySelector('video');
  enableTestMode(video);
  video.src = '../content/test.ogv';

  if (window.testRunner) {
    testRunner.waitUntilDone();
    video.requestVideoFrameCallback(() => {
      testRunner.notifyDone();
    });
  }
</script>
</html>