chromium/third_party/blink/web_tests/external/wpt/clipboard-apis/resources/page.html

<!DOCTYPE html>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-action.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="user-activation.js"></script>

<div style="width: 10px; height: 10px"></div>
<script>
window.addEventListener("message", async (e) => {
  if (e.data && e.data[0] == "write") {
    test_driver.set_test_context(window.parent);
    await tryGrantReadPermission();
    await tryGrantWritePermission();
    await waitForUserActivation();
    await navigator.clipboard.write([
      new ClipboardItem({
        "text/plain":  e.data[1],
      }),
    ]).catch(() => {
      assert_true(false, `should not fail`);
    });
    window.parent.postMessage("done", "*");
  }
});
</script>
</html>