WordPress at a glance
action is not described

make_undelete_blog action-hook . WP 3.5.0

Fires when the 'deleted' status is removed from a blog.

Usage

add_action( 'make_undelete_blog', 'action_function_name_4660' );
function action_function_name_4660( $blog_id ){
	// action...
}
$blog_id(int)
Blog ID.

Where the hook is called

update_blog_details()
make_undelete_blog
update_blog_status()
make_undelete_blog
wp-includes/ms-blogs.php 403
do_action( 'make_undelete_blog', $blog_id );
wp-includes/ms-blogs.php 1053
do_action( 'make_undelete_blog', $blog_id );

Where the hook is used (in WP core)

wp-includes/ms-default-filters.php 65
add_action( $action, 'wp_maybe_update_network_site_counts', 10, 0 );