std::chrono::system_clock with microseconds duration

MicroSecResolutionClock.h

// @brief  Created on top of std::chrono::system_clock,
//         MicroSecResolutionClock offers a clock with microseconds duration.
struct MicroSecResolutionClock : public std::chrono::system_clock {
  typedef std::chrono::microseconds duration;
  typedef duration::rep rep;
  typedef duration::period period;

  typedef std::chrono::time_point<MicroSecResolutionClock, duration> time_point;
  static const bool is_steady = false;
  static const int ticks_per_time_t = period::den;

  static time_point now() noexcept {
    auto system_clock_duration =
      std::chrono::duration< std::chrono::system_clock::rep,
      std::chrono::system_clock::period>
      (std::chrono::system_clock::now().time_since_epoch());

    return time_point(
      std::chrono::duration_cast <duration>(system_clock_duration)
    );
  }
  static
#if defined(_MSC_VER)
    __time64_t  to_time_t(const time_point& _Time) noexcept {
    return
      ((__time64_t)
#endif
#ifdef __linux__
       std::time_t  to_time_t(const time_point& _Time) noexcept {
      return
        ((std::time_t)
#endif
         (std::chrono::duration_cast <std::chrono::seconds>(_Time.time_since_epoch())
          .count()));
  }

    static
#if defined(_MSC_VER)
      time_point from_time_t(__time64_t _Tm) noexcept {
#endif
#ifdef __linux__
      time_point from_time_t(std::time_t _Tm) noexcept {
#endif      
        return
          (time_point(std::chrono::duration_cast <duration>(
            std::chrono::duration<std::chrono::seconds::rep>(_Tm))));
      }
    };