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

webrtc/rtc_base/asyncresolverinterface.h

Index: webrtc/rtc_base/asyncresolverinterface.h
diff --git a/webrtc/rtc_base/asyncresolverinterface.h b/webrtc/rtc_base/asyncresolverinterface.h
index 7b8c533b40d7d6c37abc044453cb724027ea8982..1438042f04740d8ead13282a58eca7b3cf131b3b 100644
--- a/webrtc/rtc_base/asyncresolverinterface.h
+++ b/webrtc/rtc_base/asyncresolverinterface.h
@@ -37,6 +37,7 @@ class AsyncResolverInterface {
     GetResolvedAddress(AF_INET, &addr);
     return addr;
   }
+  virtual int64_t GetResolveElapsedTimeMilliseconds() const = 0;
 
   // This signal is fired when address resolve process is completed.
   sigslot::signal1<AsyncResolverInterface*> SignalDone;