Send *Statistics and Timestamp messages from SimulatedMessageBridge

This makes the simulation environment much closer to reality.

Change-Id: Ie0f44c17d9c9a750363335def1b008cef8c809b0
diff --git a/aos/events/ping_lib.h b/aos/events/ping_lib.h
index e14c3f2..6107494 100644
--- a/aos/events/ping_lib.h
+++ b/aos/events/ping_lib.h
@@ -14,6 +14,8 @@
  public:
   Ping(EventLoop *event_loop);
 
+  void set_quiet(bool quiet) { quiet_ = quiet; }
+
  private:
   // Sends out the ping message with an incrementing count.
   void SendPing();
@@ -29,6 +31,8 @@
   int count_ = 0;
   // Last pong value received so we can detect missed pongs.
   int last_pong_value_ = 0;
+
+  bool quiet_ = false;
 };
 
 }  // namespace aos