chromium/third_party/blink/web_tests/external/wpt/remote-playback/remote-video-control-seek-manual.html

<!DOCTYPE html>
<html>
  <link rel="stylesheet" href="styles.css" />
  <title>Test that seek() on the local video is reflected on the remote device</title>
  <script src="/resources/testharness.js"></script>
  <script src="/resources/testharnessreport.js"></script>
  <script src="/common/media.js"></script>
  <script>
    setup({ explicit_timeout: true });
  </script>
  <body>
    <div id="pick-device">
      <p>
        Click the button below to prompt for a remote playback device and select
        one!
      </p>
      <p>
        Wait a few seconds for the video to initialize, play and seek.
      </p>
      <p>
        <button id="prompt-button">Pick device</button>
      </p>
    </div>
    <video src="/media/green-at-15.mp4" id="video"></video>
    <div id="evaluate" style="display: none">
      <p>
        Did the playback on the remote device pause and show the following
        timestamp? (can vary by some frames)
      </p>
      <p id="timestamp" style="font-weight: bold"></p>
      <p>
        <button id="yes">Yes</button>
      </p>
      <p>
        <button id="no">No</button>
      </p>
    </div>
  </body>
  <script>
    let v = document.getElementById("video");

    async_test(t => {
      let button = document.getElementById("prompt-button");
      button.onclick = t.step_func(() => {
        promise_test(() => {
          return v.remote.prompt().then(() => {
            v.play();
          });
        }, "Prompt resolves");
      });

      let timestampLabel = document.getElementById("timestamp");
      v.ontimeupdate = () => {
        let seconds = Math.floor(v.currentTime) + "";
        let frames = Math.ceil((v.currentTime - seconds) * 30) + "";
        timestampLabel.innerText =
          seconds.padStart(2, "0") + ":" + frames.padStart(2, "0");
        if (v.currentTime >= 2 && v.currentTime < 18) {
          v.currentTime = 18;
        }
        if (v.currentTime >= 20) {
          v.pause();
          document.getElementById("evaluate").style.display = "block";
        }
      };

      let evaluate = success =>
        assert_true(success, "Video paused and has correct play position.");

      document.getElementById("yes").onclick = t.step_func_done(() =>
        evaluate(true)
      );
      document.getElementById("no").onclick = t.step_func_done(() =>
        evaluate(false)
      );
    }, "Test that seek() on the local video is reflected on the remote device.");
  </script>
</html>