face: link layer byte counts in FaceCounters

This commit declares the counters, but does not increment the new counters.

refs #1729

Change-Id: I9cd136fc65955192a92d567629a9aba2df8090f3
diff --git a/daemon/face/face.cpp b/daemon/face/face.cpp
index 2c81a9a..4197aa5 100644
--- a/daemon/face/face.cpp
+++ b/daemon/face/face.cpp
@@ -29,12 +29,6 @@
 
 namespace nfd {
 
-static inline void
-increaseCounter(FaceCounter& counter)
-{
-  ++counter;
-}
-
 Face::Face(const FaceUri& remoteUri, const FaceUri& localUri, bool isLocal)
   : m_id(INVALID_FACEID)
   , m_isLocal(isLocal)
@@ -43,10 +37,10 @@
   , m_isOnDemand(false)
   , m_isFailed(false)
 {
-  onReceiveInterest += bind(&increaseCounter, ref(m_counters.getNInInterests()));
-  onReceiveData     += bind(&increaseCounter, ref(m_counters.getNInDatas()));
-  onSendInterest    += bind(&increaseCounter, ref(m_counters.getNOutInterests()));
-  onSendData        += bind(&increaseCounter, ref(m_counters.getNOutDatas()));
+  onReceiveInterest += bind(&PacketCounter::operator++, &m_counters.getNInInterests());
+  onReceiveData     += bind(&PacketCounter::operator++, &m_counters.getNInDatas());
+  onSendInterest    += bind(&PacketCounter::operator++, &m_counters.getNOutInterests());
+  onSendData        += bind(&PacketCounter::operator++, &m_counters.getNOutDatas());
 }
 
 Face::~Face()
@@ -59,7 +53,7 @@
   return m_id;
 }
 
-// this method is private and should be used only by the Forwarder
+// this method is private and should be used only by the FaceTable
 void
 Face::setId(FaceId faceId)
 {