chromium/third_party/blink/web_tests/external/wpt/permissions/permissions-garbage-collect.https.html

<!DOCTYPE html>
<meta charset="utf-8" />
<title>Test Permission garbage collection persistance.</title>
<link rel="help" href="https://github.com/w3c/permissions/pull/256" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<body>
  <script>
    async function createABunchOfGarbage() {
      const promises = [];
      for (let i = 0; i < 25; i++) {
        const promise = new Promise((r) => {
          const iframe = document.createElement("iframe");
          iframe.onload = () => r(iframe);
          iframe.src = "about:blank";
          document.body.appendChild(iframe);
        });
        promises.push(promise);
      }
      const iframes = await Promise.all(promises);
      iframes.forEach((iframe) => iframe.remove());
    }

    promise_test(async (t) => {
      t.add_cleanup(() => {
        return test_driver.set_permission({ name: "geolocation" }, "prompt");
      });

      const eventPromise = new Promise(
        async (r) => {
          // we create the status here, but it goes out of scope
          // at the end of the function. Thus, we assume it will be
          // garbage collected.
          const status = await navigator.permissions.query({
            name: "geolocation",
          });
          status.addEventListener("change", r);
        },
        { once: true }
      );

      // Maybe got garbage collected.
      await createABunchOfGarbage();

      // Causes event to fire.
      await test_driver.set_permission({ name: "geolocation" }, "granted");
      await eventPromise;
    }, "Events fire even if the status object is garbage collected");
  </script>
</body>