signal-desktop/libtextsecure/protobufs.js

;(function() {
    'use strict';
    window.textsecure = window.textsecure || {};
    window.textsecure.protobuf = {};

    function loadProtoBufs(filename) {
        return dcodeIO.ProtoBuf.loadProtoFile({root: window.PROTO_ROOT, file: filename}, function(error, result) {
            if (error) {
                var text = 'Error loading protos from ' + filename + ' (root: ' + window.PROTO_ROOT + ') '
                    + (error && error.stack ? error.stack : error);
                console.log(text);
                throw error;
            }
            var protos = result.build('signalservice');
            if (!protos) {
                var text = 'Error loading protos from ' + filename + ' (root: ' + window.PROTO_ROOT + ')';
                console.log(text);
                throw new Error(text);
            }
            for (var protoName in protos) {
                textsecure.protobuf[protoName] = protos[protoName];
            }
        });
    };

    loadProtoBufs('SignalService.proto');
    loadProtoBufs('SubProtocol.proto');
    loadProtoBufs('DeviceMessages.proto');
})();