code: func (p *implementation) transport(c context.Context) (transport http.RoundTripper, err error) {
  	luciProject, err := ProjectFromContext(c)
  	if err != nil {
  		return nil, err
  	}
  	opts := []auth.RPCOption{
  		auth.WithProject(luciProject),
  		auth.WithScopes(gitiles.OAuthScope),
  	}
  	return auth.GetRPCTransport(c, auth.AsProject, opts...)
  }
docs: // transport returns an authenticated RoundTripper for Gerrit or Gitiles RPCs.