helpers: Update face metric based on simulated p2p link delay

Change-Id: I75098293f631b6bc7f6fbd58413e7756f19d0865
refs: #4733
diff --git a/helper/ndn-stack-helper.hpp b/helper/ndn-stack-helper.hpp
index bae814f..2d2b8fb 100644
--- a/helper/ndn-stack-helper.hpp
+++ b/helper/ndn-stack-helper.hpp
@@ -248,6 +248,12 @@
   void
   disableForwarderStatusManager();
 
+  /**
+   * @brief Set face metric of all faces connected through PointToPoint channel to channel latency
+   */
+  static void
+  SetLinkDelayAsFaceMetric();
+
 private:
   shared_ptr<Face>
   DefaultNetDeviceCallback(Ptr<Node> node, Ptr<L3Protocol> ndn, Ptr<NetDevice> netDevice) const;