Add logging of host lookups made by TurnPort to the RtcEventLog.

webrtc/logging/rtc_event_log/rtc_event_log.h

Index: webrtc/logging/rtc_event_log/rtc_event_log.h
diff --git a/webrtc/logging/rtc_event_log/rtc_event_log.h b/webrtc/logging/rtc_event_log/rtc_event_log.h
index dc3351120c89d458222e715ad0a872f5804dc2c7..33d6f806cd06c7dab87631c71a056ff47172278f 100644
--- a/webrtc/logging/rtc_event_log/rtc_event_log.h
+++ b/webrtc/logging/rtc_event_log/rtc_event_log.h
@@ -170,6 +170,12 @@ class RtcEventLog {
   virtual void LogProbeResultFailure(int id,
                                      ProbeFailureReason failure_reason) = 0;
 
+  // Logs the result of a host lookup.
+  virtual void LogHostLookupResult(const std::string& hostname,
+                                   int error,
+                                   const std::string& result,
+                                   int64_t elapsed_time_in_microseconds) = 0;
+
   // Reads an RtcEventLog file and returns true when reading was successful.
   // The result is stored in the given EventStream object.
   // The order of the events in the EventStream is implementation defined.
@@ -224,6 +230,11 @@ class RtcEventLogNullImpl : public RtcEventLog {
   void LogProbeResultSuccess(int id, int bitrate_bps) override{};
   void LogProbeResultFailure(int id,
                              ProbeFailureReason failure_reason) override{};
+
+  void LogHostLookupResult(const std::string& hostname,
+                           int error,
+                           const std::string& result,
+                           int64_t elapsed_time_in_microseconds) override {}
 };
 
 }  // namespace webrtc