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

webrtc/logging/rtc_event_log/rtc_event_log.proto

Index: webrtc/logging/rtc_event_log/rtc_event_log.proto
diff --git a/webrtc/logging/rtc_event_log/rtc_event_log.proto b/webrtc/logging/rtc_event_log/rtc_event_log.proto
index b9053ae87dabd5082587226c396cfed09825a06a..fac78dcc11e2de0e4ebf929ccc97033a35804de4 100644
--- a/webrtc/logging/rtc_event_log/rtc_event_log.proto
+++ b/webrtc/logging/rtc_event_log/rtc_event_log.proto
@@ -40,6 +40,7 @@ message Event {
     AUDIO_NETWORK_ADAPTATION_EVENT = 16;
     BWE_PROBE_CLUSTER_CREATED_EVENT = 17;
     BWE_PROBE_RESULT_EVENT = 18;
+    HOST_LOOKUP_EVENT = 19;
   }
 
   // required - Indicates the type of this event
@@ -81,6 +82,9 @@ message Event {
 
     // required if type == BWE_PROBE_RESULT_EVENT
     BweProbeResult probe_result = 18;
+
+    // required if type == HOST_LOOKUP_EVENT
+    HostLookupResult host_lookup_result = 19;
   }
 }
 
@@ -314,3 +318,12 @@ message BweProbeResult {
   // optional - but required if result == SUCCESS. The resulting bitrate in bps.
   optional uint64 bitrate_bps = 3;
 }
+
+message HostLookupResult {
+  // required - error code or 0 for OK
+  optional int32 error = 1;
+
+  // required - Time elapsed for lookup in milliseconds.
+  optional int64 host_lookup_time_ms = 2;
+}
+