<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <script>
      window.onmessage = function (event) {
        if (event.data !== "register") {
          return;
        }
        var promise = navigator.serviceWorker.register("worker.js",
                                                       { updateViaCache: 'all' });
        window.onmessage = function (e) {
          if (e.data !== "unregister") {
            return;
          }
          promise.then(function (registration) {
            registration.unregister();
          });
          window.onmessage = null;
        };
      };
    </script>
  </head>
  <body>
    This is a test page.
  </body>
<html>
