bp_update_to_1_9()

function bp_update_to_1_9() {

	// Setup hardcoded keys.
	$active_components_key      = 'bp-active-components';
	$notifications_component_id = 'notifications';

	// Get the active components.
	$active_components          = bp_get_option( $active_components_key );

	// Add notifications.
	if ( ! in_array( $notifications_component_id, $active_components ) ) {
		$active_components[ $notifications_component_id ] = 1;
	}

	// Update the active components option.
	bp_update_option( $active_components_key, $active_components );
}