It looks like the problem had been resolved with the latest Chrome update... I'm running the Chrome Version 36.0.1964.4 dev-m.
I was limited too warning the user from closing print preview window by doing the following:
if(navigator.userAgent.toLowerCase().indexOf('chrome') > -1){ // Chrome Browser Detected?
window.PPClose = false; // Clear Close Flag
window.onbeforeunload = function(){ // Before Window Close Event
if(window.PPClose === false){ // Close not OK?
return 'Leaving this page will block the parent window!\nPlease select "Stay on this Page option" and use the\nCancel button instead to close the Print Preview Window.\n';
}
}
window.print(); // Print preview
window.PPClose = true; // Set Close Flag to OK.
}
Now the warning is no longer coming up after the Chrome update.