/**
   * Bootstraps the app.
   *
   * @param theme The theme to apply to the app.
   */
  bootstrap(theme: Theme = DEFAULT_THEME_, customElements: gs.ICtor<BaseDisposable>[] = []): void {
    const ctors = ImmutableSet.of(DEFAULT_ELEMENTS_).addAll(ImmutableSet.of(customElements));
    for (const ctor of ctors) {
      this.registrar_.register(ctor);
    }

    this.themeService_.install(theme);
  }

export function providesRouteFactoryMap<T>(
    routeFactories: Iterable<RouteFactory<T>>): RouteFactoryMap<T> {
  return ImmutableMap.of(
      ImmutableSet.of([...routeFactories])
          .mapItem((factory: RouteFactory<T>) => {
            return [factory.getType(), factory] as [T, RouteFactory<T>];
          }));
}

  /**
   * @param bundleId ID of the bundle to process.
   * @return Promise that will be resolved with a map of File to its content, or null if the
   *     bundle ID does not exist.
   */
  async processBundle(bundleId: string): Promise<Map<File, string> | null> {
    const files = this.getBundle(bundleId);
    if (files === null) {
      return Promise.resolve(null);
    }

    const promises = ImmutableSet
        .of(files)
        .mapItem((file: File) => {
          return Promise.all([file, this.processFile_(file)]);
        });
    return new Map(await Promise.all(promises));
  }