RegisterRLSChildPolicy registers a balancer builder with the given name, to be used as a child policy for the RLS LB policy.

RLSChildPolicyBadTarget is a value which is considered a bad target by the child policy.

RLSChildPolicyTargetNameField is a top-level field name to add to the child policy's config, whose value is set to the target for the child policy.

ErrParseConfigBadTarget is the error returned from ParseConfig when the backend field is set to RLSChildPolicyBadTarget.

BalancerFuncs is a set of callbacks which get invoked when the corresponding method on the child policy is invoked.

RLSChildPolicyConfig is the LB config for the test child policy.

RLSConfig is a utility type to build service config for the RLS LB policy.