<!DOCTYPE html>
<html>
<body>
<iframe src="frame-do-load.html" id="doLoadSubframe"></iframe>
<script>
window.addEventListener("pagehide", function(event) {
    // Start load in subframe.
    var subframe = document.getElementById("doLoadSubframe");
    subframe.contentWindow.doLoad();
}, false);
</script>
</body>
</html>