<!DOCTYPE html>
<a href="file_use_counter_bfcache_helper.html?b">b</a>
<a href="file_use_counter_bfcache_helper.html?c">c</a>
<svg></svg>
<script>
let which = location.search.substring(1);

if (which == "c") {
  // Set the sentinel use counter.
  let s = document.createElement("style");
  s.textContent = "g { marker-mid: none; }";
  document.body.append(s);
}

onload = function() {
  window.opener.postMessage(`${which}-doc-loaded`, "*");
};

onmessage = function() {
  switch (event.data) {
    case "click-b-link":
      document.querySelectorAll("a")[0].click();
      break;
    case "click-c-link":
      document.querySelectorAll("a")[1].click();
      break;
    case "go-back":
      history.back();
      break;
    case "set-use-counter":
      document.querySelector("svg").getElementById("x");
      window.opener.postMessage("did-set-use-counter", "*");
      break;
  }
};

onpageshow = function() {
  window.opener.postMessage(`${which}-doc-shown`, "*");
};
</script>
