function refreshFileSystems(callback)
        {
            var barrier = new CallbackBarrier();
            var projects = this._workspace.projects();
            for (var i = 0; i < projects.length; ++i)
                projects[i].refresh("/", barrier.createCallback());
            barrier.callWhenDone(callback);
        }
@this {WebInspector.WorkspaceController}
@param {!WebInspector.Throttler.FinishCallback} callback