Refactor diff into sub pkg

pkg/kubelet/pleg/generic_test.go

@@ -28,6 +28,7 @@ import (
 	containertest "k8s.io/kubernetes/pkg/kubelet/container/testing"
 	"k8s.io/kubernetes/pkg/types"
 	"k8s.io/kubernetes/pkg/util"
+	"k8s.io/kubernetes/pkg/util/diff"
 )
 
 const (
@@ -86,7 +87,7 @@ func verifyEvents(t *testing.T, expected, actual []*PodLifecycleEvent) {
 	sort.Sort(sortableEvents(expected))
 	sort.Sort(sortableEvents(actual))
 	if !reflect.DeepEqual(expected, actual) {
-		t.Errorf("Actual events differ from the expected; diff:\n %v", util.ObjectDiff(expected, actual))
+		t.Errorf("Actual events differ from the expected; diff:\n %v", diff.ObjectDiff(expected, actual))
 	}
 }