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

webrtc/rtc_base/nethelpers.cc

Index: webrtc/rtc_base/nethelpers.cc
diff --git a/webrtc/rtc_base/nethelpers.cc b/webrtc/rtc_base/nethelpers.cc
index 8489970b392dc7dbe15c3211e38977b9cc52eecd..a79816d298b8a04bbfa099feafc73682ed6d6a9f 100644
--- a/webrtc/rtc_base/nethelpers.cc
+++ b/webrtc/rtc_base/nethelpers.cc
@@ -108,6 +108,10 @@ bool AsyncResolver::GetResolvedAddress(int family, SocketAddress* addr) const {
   return false;
 }
 
+int64_t AsyncResolver::GetResolveElapsedTimeMilliseconds() const {
+  return resolve_time_ms_;
+}
+
 int AsyncResolver::GetError() const {
   return error_;
 }
@@ -117,8 +121,11 @@ void AsyncResolver::Destroy(bool wait) {
 }
 
 void AsyncResolver::DoWork() {
+  int64_t start = rtc::TimeMillis();
   error_ = ResolveHostname(addr_.hostname().c_str(), addr_.family(),
                            &addresses_);
+  int64_t stop = rtc::TimeMillis();
+  resolve_time_ms_ = stop - start;
 }
 
 void AsyncResolver::OnWorkDone() {