plugin/kubernetes: Fix dns programming duration metric (#4255)

* get data reqd to record latency before calling toFuncs
* refactor out unnecessary toFunc wrappers
* remove latency metric unit tests per PR feedback

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

plugin/kubernetes/object/service.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	api "k8s.io/api/core/v1"
+	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 )
 
@@ -28,18 +29,12 @@ type Service struct {
 // ServiceKey returns a string using for the index.
 func ServiceKey(name, namespace string) string { return name + "." + namespace }
 
-// ToService returns a function that converts an api.Service to a *Service.
-func ToService(skipCleanup bool) ToFunc {
-	return func(obj interface{}) (interface{}, error) {
-		svc, ok := obj.(*api.Service)
-		if !ok {
-			return nil, fmt.Errorf("unexpected object %v", obj)
-		}
-		return toService(skipCleanup, svc), nil
+// ToService converts an api.Service to a *Service.
+func ToService(obj meta.Object) (meta.Object, error) {
+	svc, ok := obj.(*api.Service)
+	if !ok {
+		return nil, fmt.Errorf("unexpected object %v", obj)
 	}
-}
-
-func toService(skipCleanup bool, svc *api.Service) *Service {
 	s := &Service{
 		Version:      svc.GetResourceVersion(),
 		Name:         svc.GetName(),
@@ -70,11 +65,9 @@ func toService(skipCleanup bool, svc *api.Service) *Service {
 
 	}
 
-	if !skipCleanup {
-		*svc = api.Service{}
-	}
+	*svc = api.Service{}
 
-	return s
+	return s, nil
 }
 
 var _ runtime.Object = &Service{}