Use jQuery('#navbar').accountChooser('showAccountChooser'); to call
the public method 'showAccountChooser' on the widget.
(See some description about the syntax to call public method on a
jQuery UI widget at:
http://stackoverflow.com/questions/1596137/how-do-i-reference-a-jquery-ui-widget-on-a-page-and-call-a-function-on-it
)
As result, your code should be something like below:
jQuery(function(){
window.google.identitytoolkit.easyrp.config.setConfig({
............... });
jQuery('#navbar').accountChooser(); ........
jQuery('#navbar').accountChooser('showAccountChooser');});</script>