How to Add a Default Site Icon in Theme's Customizer

Okay I am trying to add a default Site Icon for my theme that I am building for a client. I have done something similar for their site logo.

// Site Logo Upload
$wp_customize->add_setting( 'site_logo_upload', array (
'default' => get_stylesheet_directory_uri() . '/assets/images/psad_logo.png'
) );

Would I just write up the same thing to add a default site icon, but replacing the setting name to what it would be for the site icon? If so what is the setting name for the site icon?

Thank you in advance