function maybeInitialize(info, loadingModuleIds) {
  if (!moduleManager) {
    if (!getDefault) return;
    set(getDefault());
  }
  moduleManager.setAllModuleInfoString(info, loadingModuleIds);
}
Initialize the module manager.
@param {string=} info A string representation of the module dependency
     graph, in the form: module1:dep1,dep2/module2:dep1,dep2 etc.
    Where depX is the base-36 encoded position of the dep in the module list.
@param {!Array<string>=} loadingModuleIds A list of moduleIds that
    are currently being loaded.