WordPress at a glance
filter is not described

theme_root_uri filter-hook . WP 1.5.0

Filters the URI for themes directory.

Usage

add_filter( 'theme_root_uri', 'filter_function_name_6073', 10, 3 );
function filter_function_name_6073( $theme_root_uri, $siteurl, $stylesheet_or_template ){
	// filter...

	return $theme_root_uri;
}
$theme_root_uri(string)
The URI for themes directory.
$siteurl(string)
WordPress web address which is set in General Options.
$stylesheet_or_template(string)
Stylesheet or template name of the theme.

Where the hook is called

get_theme_root_uri()
theme_root_uri
wp-includes/theme.php 613
return apply_filters( 'theme_root_uri', $theme_root_uri, get_option( 'siteurl' ), $stylesheet_or_template );

Where the hook is used (in WP core)

Does not used.