Add Auth to Xhr fetch

[CMalmos]

protobuf.js version: head

it is not possible to make protobuff files private how do i add headers in the fetch lib

i want to be able to do something like
protobbuff.load(url , ... {headers: {Authentication: "Bearer Token"})

and in util/fetch/index.js

fetch_xhr(filename, options, callback)
 xhr.open("GET", filename);

    if (options.headers){
        for (var key in options.headers) {
            if (options.headers.hasOwnProperty(key)) {
                xhr.setRequestHeader(key, options.headers[key]);
            }
        }
    }
    xhr.send();

Or is here another way to do this?