[ndnSIM] face: Enable metric parameter on a face

Change-Id: I1de7298835af1fb329e356cbe74c3ac29fc53cea
diff --git a/daemon/face/face.hpp b/daemon/face/face.hpp
index 5486a43..1a69cb5 100644
--- a/daemon/face/face.hpp
+++ b/daemon/face/face.hpp
@@ -119,6 +119,12 @@
   void
   setId(FaceId id);
 
+  void
+  setMetric(uint64_t metric);
+
+  uint64_t
+  getMetric() const;
+
   /** \return a FaceUri representing local endpoint
    */
   FaceUri
@@ -186,6 +192,7 @@
   unique_ptr<LinkService> m_service;
   unique_ptr<Transport> m_transport;
   FaceCounters m_counters;
+  uint64_t m_metric;
 };
 
 inline LinkService*
@@ -230,6 +237,18 @@
   m_id = id;
 }
 
+inline void
+Face::setMetric(uint64_t metric)
+{
+  m_metric = metric;
+}
+
+inline uint64_t
+Face::getMetric() const
+{
+  return m_metric;
+}
+
 inline FaceUri
 Face::getLocalUri() const
 {