[ndnSIM] fw: Keep both the CS of NFD and ndnSIM

Ref: #2231
diff --git a/daemon/fw/forwarder.hpp b/daemon/fw/forwarder.hpp
index aa5d19d..c8bd402 100644
--- a/daemon/fw/forwarder.hpp
+++ b/daemon/fw/forwarder.hpp
@@ -37,6 +37,8 @@
 #include "table/strategy-choice.hpp"
 #include "table/dead-nonce-list.hpp"
 
+#include "ns3/ndnSIM/model/cs/ndn-content-store.hpp"
+
 namespace nfd {
 
 namespace fw {
@@ -104,6 +106,10 @@
   DeadNonceList&
   getDeadNonceList();
 
+public: // allow enabling ndnSIM content store (will be removed in the future)
+  void
+  setCsFromNdnSim(ns3::Ptr<ns3::ndn::ContentStore> cs);
+
 PUBLIC_WITH_TESTS_ELSE_PRIVATE: // pipelines
   /** \brief incoming Interest pipeline
    */
@@ -210,6 +216,8 @@
   StrategyChoice m_strategyChoice;
   DeadNonceList  m_deadNonceList;
 
+  ns3::Ptr<ns3::ndn::ContentStore> m_csFromNdnSim;
+
   static const Name LOCALHOST_NAME;
 
   // allow Strategy (base class) to enter pipelines
@@ -294,6 +302,12 @@
   return m_deadNonceList;
 }
 
+inline void
+Forwarder::setCsFromNdnSim(ns3::Ptr<ns3::ndn::ContentStore> cs)
+{
+  m_csFromNdnSim = cs;
+}
+
 #ifdef WITH_TESTS
 inline void
 Forwarder::dispatchToStrategy(shared_ptr<pit::Entry> pitEntry, function<void(fw::Strategy*)> trigger)