Always set content-type & nosniff

cmd/kube-scheduler/app/server.go

@@ -299,6 +299,8 @@ func installMetricHandler(pathRecorderMux *mux.PathRecorderMux) {
 	pathRecorderMux.HandleFunc("/metrics", func(w http.ResponseWriter, req *http.Request) {
 		if req.Method == "DELETE" {
 			metrics.Reset()
+			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+			w.Header().Set("X-Content-Type-Options", "nosniff")
 			io.WriteString(w, "metrics reset\n")
 			return
 		}