download blob using dropbox Saver

Hi,

I am trying to use the dropbox Saver (https://www.dropbox.com/developers/saver) to download a json blob from my desktop (ubuntu).

This leads to an error:  Url "blob:http://localhost:5000/f58ddb0b-48ed-46ab-87b3-f45a1ee8a7df" uses unsupported scheme

Is it possible to download a blob using Saver ? If so, any ideas what I am doing wrong? 

The code i used is as follows: with url = blob:http://localhost:5000/f58ddb0b-48ed-46ab-87b3-f45a1ee8a7df", and filename = "yourmap.json"

Thanks, 

Joost

function create_dropbox_save_button(url, mapname){
    var options = {  
        success: function () {
            // Indicate to the user that the files have been saved.
            alert("Success! Files saved to your Dropbox.");
        },
        progress: function (progress) {console.log(progress)},
        cancel: function () {},
        error: function (errorMessage) {console.log(errorMessage)}
    };
    var button = Dropbox.createSaveButton(url, mapname, options);
    document.getElementById("dl_dropbox").appendChild(button);
}