[BattOr] Make BattOr able to return firmware version.

tools/battor_agent/battor_agent.h

Index: tools/battor_agent/battor_agent.h
diff --git a/tools/battor_agent/battor_agent.h b/tools/battor_agent/battor_agent.h
index 810df26936af2cf15d4c72845937aa7fac8da676..3438eec188bbf0acae9ae80ae04cf34230ac5bc1 100644
--- a/tools/battor_agent/battor_agent.h
+++ b/tools/battor_agent/battor_agent.h
@@ -43,6 +43,7 @@ class BattOrAgent : public BattOrConnection::Listener,
     virtual void OnStopTracingComplete(const std::string& trace,
                                        BattOrError error) = 0;
     virtual void OnRecordClockSyncMarkerComplete(BattOrError error) = 0;
+    virtual void OnGetVersionComplete(const int version, BattOrError error) = 0;
   };
 
   BattOrAgent(
@@ -55,6 +56,7 @@ class BattOrAgent : public BattOrConnection::Listener,
   void StartTracing();
   void StopTracing();
   void RecordClockSyncMarker(const std::string& marker);
+  void GetVersion();
 
   // Returns whether the BattOr is able to record clock sync markers in its own
   // trace log.
@@ -85,6 +87,7 @@ class BattOrAgent : public BattOrConnection::Listener,
     START_TRACING,
     STOP_TRACING,
     RECORD_CLOCK_SYNC_MARKER,
+    GET_VERSION,
   };
 
   enum class Action {