Add logging host lookups made by TurnPort to the RtcEventLog.

The following fields are logged:
- error, if there was an error.
- elapsed time in milliseconds

BUG=webrtc:8100

Review-Url: https://codereview.webrtc.org/2996933003
Cr-Commit-Position: refs/heads/master@{#19574}

webrtc/rtc_tools/event_log_visualizer/analyzer.cc

@@ -509,6 +509,10 @@ EventLogAnalyzer::EventLogAnalyzer(const ParsedRtcEventLog& log)
         bwe_probe_result_events_.push_back(parsed_log_.GetBweProbeResult(i));
         break;
       }
+      case ParsedRtcEventLog::HOST_LOOKUP_EVENT: {
+        // TODO(jonaso): What to do ??
+        break;
+      }
       case ParsedRtcEventLog::UNKNOWN_EVENT: {
         break;
       }