LogDog: Add prefix registration endpoint.

common/api/logdog_coordinator/registration/v1/registrationserver_dec.go

Index: common/api/logdog_coordinator/registration/v1/registrationserver_dec.go
diff --git a/common/api/logdog_coordinator/admin/v1/adminserver_dec.go b/common/api/logdog_coordinator/registration/v1/registrationserver_dec.go
similarity index 61%
copy from common/api/logdog_coordinator/admin/v1/adminserver_dec.go
copy to common/api/logdog_coordinator/registration/v1/registrationserver_dec.go
index f4d13b46b9c3940ddfd6a2c0e93601162e4e839f..b6c9d9f092945028c0b539138825bebd2db5303b 100644
--- a/common/api/logdog_coordinator/admin/v1/adminserver_dec.go
+++ b/common/api/logdog_coordinator/registration/v1/registrationserver_dec.go
@@ -5,22 +5,20 @@ package logdog
 import (
 	proto "github.com/golang/protobuf/proto"
 	context "golang.org/x/net/context"
-
-	google_protobuf "github.com/luci/luci-go/common/proto/google"
 )
 
-type DecoratedAdmin struct {
+type DecoratedRegistration struct {
 	// Service is the service to decorate.
-	Service AdminServer
+	Service RegistrationServer
 	// Prelude is called in each method before forwarding the call to Service.
 	// If Prelude returns an error, it is returned without forwarding the call.
 	Prelude func(c context.Context, methodName string, req proto.Message) (context.Context, error)
 }
 
-func (s *DecoratedAdmin) SetConfig(c context.Context, req *SetConfigRequest) (*google_protobuf.Empty, error) {
-	c, err := s.Prelude(c, "SetConfig", req)
+func (s *DecoratedRegistration) RegisterPrefix(c context.Context, req *RegisterPrefixRequest) (*RegisterPrefixResponse, error) {
+	c, err := s.Prelude(c, "RegisterPrefix", req)
 	if err != nil {
 		return nil, err
 	}
-	return s.Service.SetConfig(c, req)
+	return s.Service.RegisterPrefix(c, req)
 }