rejectAllPromises_() {
    if (!this.asyncCallPromises_) {
      return;
    }
    for (const id of this.asyncCallPromises_.keys()) {
      const p = this.asyncCallPromises_.get(id);
      this.asyncCallPromises_.delete(id);

      // Reject pending async operations as if they were interrupted.
      // At the moment, load() is the only async operation we are worried about.
      p.reject(new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.LOAD_INTERRUPTED));
    }
  }
Reject any async call promises that are still pending.
@private