Adding event listeners for notifications

basic_notification_event_listener.js

// Add listener for onClicked event.
browser.notifications.onClicked.addListener(function (notificationid) {
    window.alert(notificationid + " clicked");
});

// Add listener for onButtonClicked event.
browser.notifications.onButtonClicked.addListener(function (notificationid, buttonIndex) {
    window.alert("Button " + buttonIndex + " of " + notificationid + " clicked");
});

// Add listener for onClosed event.
browser.notifications.onClosed.addListener(function (notificationid, byUser) {
    window.alert("Notification " + notificationid + " closed " + (byUser ? "by user" : "automatically due to timeout"));
});