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..e5e4ea6c7dc278159e02e941dc654139c67467cc 100644
--- a/webrtc/rtc_base/nethelpers.cc
+++ b/webrtc/rtc_base/nethelpers.cc
@@ -84,7 +84,8 @@ int ResolveHostname(const std::string& hostname, int family,
 
 // AsyncResolver
 AsyncResolver::AsyncResolver()
-    : SignalThread(false /* use_socket_server */), error_(-1) {}
+    : SignalThread(false /* use_socket_server */),
+      error_(-1), resolve_time_ms_(0) {}
 
 AsyncResolver::~AsyncResolver() = default;
 
@@ -108,6 +109,10 @@ 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 +122,11 @@ 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() {