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..f2d623fe8ccb8387b2c201148722f959225949cd 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 +318,18 @@ message BweProbeResult {
   // optional - but required if result == SUCCESS. The resulting bitrate in bps.
   optional uint64 bitrate_bps = 3;
 }
+
+message HostLookupResult {
+  // optional - hostname.
+  optional string hostname = 1;

[terelius, 2017/08/16 14:19:06]

Generally speaking, we don't want to have strings in the proto. Is this really
necessary?

+
+  // required - error code.
+  optional int32 error = 2;
+
+  // optional - resulting IP address (anonymized).
+  optional string lookup_result = 3;

[terelius, 2017/08/16 14:19:07]

Same here. How do we guarantee anonymization?

+
+  // required - Time elapsed for lookup.
+  optional int64 elapsed_time_in_microseconds = 4;

[terelius, 2017/08/16 14:19:06]

Is microsecond accuracy needed here?

+}
+