mgmt: expose link layer counters in Face Dataset

refs #1767

Change-Id: If0b66ead4c2f2741c83396f251cce9a0d83c1520
diff --git a/daemon/fw/forwarder-counters.hpp b/daemon/fw/forwarder-counters.hpp
index 7af679a..ba3b57c 100644
--- a/daemon/fw/forwarder-counters.hpp
+++ b/daemon/fw/forwarder-counters.hpp
@@ -34,9 +34,18 @@
  */
 class ForwarderCounters : public NetworkLayerCounters
 {
+public:
+  /** \brief copy current obseverations to a struct
+   *  \param recipient an object with set methods for counters
+   */
+  template<typename R>
+  void
+  copyTo(R& recipient) const
+  {
+    this->NetworkLayerCounters::copyTo(recipient);
+  }
 };
 
-
 } // namespace nfd
 
 #endif // NFD_DAEMON_FW_FORWARDER_COUNTERS_HPP