face: remove nfd::ProtocolFactory type alias

Change-Id: Iac0af82a5301245e621a39f3bfc98aaed8dbaa45
diff --git a/tests/daemon/mgmt/face-manager.t.cpp b/tests/daemon/mgmt/face-manager.t.cpp
index c953d3b..8856b0a 100644
--- a/tests/daemon/mgmt/face-manager.t.cpp
+++ b/tests/daemon/mgmt/face-manager.t.cpp
@@ -249,7 +249,7 @@
   }
 };
 
-class TestProtocolFactory : public ProtocolFactory
+class TestProtocolFactory : public face::ProtocolFactory
 {
 public:
   void