[ndnSIM] core: Make use of scheduler redirection from ndn-cxx library (avoid code duplication)

Change-Id: I238dff4f25f07cdd05f96714c3dbeca01327c26d
diff --git a/core/scheduler.hpp b/core/scheduler.hpp
index 8c9db68..6e87199 100644
--- a/core/scheduler.hpp
+++ b/core/scheduler.hpp
@@ -27,27 +27,31 @@
 #define NFD_CORE_SCHEDULER_HPP
 
 #include "common.hpp"
-
-#include "ns3/simulator.h"
+#include <ndn-cxx/util/scheduler.hpp>
 
 namespace nfd {
 namespace scheduler {
 
+using ndn::Scheduler;
+
 /** \class EventId
  *  \brief Opaque type (shared_ptr) representing ID of a scheduled event
  */
-typedef std::shared_ptr<ns3::EventId> EventId;
+using ndn::EventId;
 
 /** \brief schedule an event
  */
 EventId
-schedule(const time::nanoseconds& after, const std::function<void()>& event);
+schedule(const time::nanoseconds& after, const Scheduler::Event& event);
 
 /** \brief cancel a scheduled event
  */
 void
 cancel(const EventId& eventId);
 
+Scheduler&
+getGlobalScheduler();
+
 /** \brief cancels an event automatically upon destruction
  */
 class ScopedEventId : noncopyable