<!DOCTYPE html>
<script>
let goneBack = false;
let w;

onload = function() {
  w = window.open("file_use_counter_bfcache_helper.html?a", "_blank");
};

onmessage = function() {
  switch (event.data) {
    case "a-doc-loaded":
      if (!goneBack) {
        w.postMessage("click-b-link", "*");
      }
      break;
    case "b-doc-loaded":
      if (!goneBack) {
        goneBack = true;
        w.postMessage("go-back", "*");
      }
      break;
    case "a-doc-shown":
      if (goneBack) {
        w.postMessage("set-use-counter", "*");
      }
      break;
    case "did-set-use-counter":
      w.postMessage("click-c-link", "*");
      break;
    case "c-doc-loaded":
      w.close();
      // Signal that we've finished.
      location.hash = "#finished";
      break;
  }
};
</script>
