Instead of giving the function a bound, a scope, a property to update and a callback, only give the bound and a callback. When the url is retrieved by getUrlAsync, simply call the callback with the url as argument and let the caller manage this.
Instead of giving the function a bound, a scope, a property to update and a callback, only give the bound and a callback. When the url is retrieved by getUrlAsync, simply call the callback with the url as argument and let the caller manage this.