makeNetworkRequest_(request, type, context) {
    if (!this.operationManager_) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.OPERATION_ABORTED);
    }

    if (!context) {
      context = {};
    }
    context.isPreload = this.isPreloadFn_();
    const op = this.playerInterface_.networkingEngine.request(
        type, request, context);
    this.operationManager_.manage(op);

    return op;
  }
Create a networking request. This will manage the request using the
parser's operation manager. If the parser has already been stopped, the
request will not be made.

@param {shaka.extern.Request} request
@param {shaka.net.NetworkingEngine.RequestType} type
@param {shaka.extern.RequestContext=} context
@return {!shaka.net.NetworkingEngine.PendingRequest}
@private