WordPress at a glance
action is not described

customize_save_after action-hook . WP 3.6.0

Fires after Customize settings have been saved.

Usage

add_action( 'customize_save_after', 'action_function_name_5941' );
function action_function_name_5941( $manager ){
	// action...
}
$manager(WP_Customize_Manager)
WP_Customize_Manager instance.

Where the hook is called

WP_Customize_Manager::_publish_changeset_values()
customize_save_after
wp-includes/class-wp-customize-manager.php 3476
do_action( 'customize_save_after', $this );

Where the hook is used (in WP core)

wp-admin/custom-header.php 61
add_action( 'customize_save_after', array( $this, 'customize_set_last_used' ) );
wp-includes/default-filters.php 236
add_action( $action, '_delete_option_fresh_site', 0 );