Umbraco : get relative URL of IContent without UmbracoContext

ContentExtensions.cs

public static class ContentExtensions
{                
    public static string RelativeUrl(this IContent content)
    {
        var pathParts = new List<string>();
        var n = content;

        while (n != null)
        {
            pathParts.Add(n.UrlName());
            n = n.Parent();                
        }
        pathParts.RemoveAt(pathParts.Count() - 1); //remove root node
        pathParts.Reverse();
        var path = "/" + string.Join("/", pathParts);
        return path;
    }    

    public static string UrlName(this IContent content)
    {
        return new DefaultUrlSegmentProvider().GetUrlSegment(content).ToLower();
    }     
}