How to get circular frameless window like new widget widget with Chrome apps

I am trying to create a chrome app with similar widgets like the new google hangout on desktops. I've done some reading on frameless borders and downloaded some sample chrome apps, but none of them provide a feature that lets you customize the shape of the frame.

I would really appreciate a solution. Java makes this possible by creating a Graphics2D and setting a JFrame to that form. looks something like this.

/*
 * Creates new form Widget
 */
public Widget() {
    //initComponents();
    super("Widget");
    initComponents();
    setLayout(new GridBagLayout());
    addComponentListener(new ComponentAdapter() {
        @Override
        public void componentResized(ComponentEvent e) {
            Ellipse2D frame = new Ellipse2D.Double(0, 0, getWidth(), getWidth());
            setShape(frame);

        }
    });
}

      

        
        
        
      

    

I am hoping to get this similar functionality in chrome apps.