Roll forward to cl/340537221

Signed-off-by: hai007 <hais@google.com>

cpp/platform/impl/g3/webrtc.cc

@@ -32,6 +32,10 @@ void WebRtcSignalingMessenger::StopReceivingMessages() {
   env.UnregisterWebRtcSignalingMessenger(self_id_);
 }
 
+const std::string WebRtcMedium::GetDefaultCountryCode() {
+  return "US";
+}
+
 void WebRtcMedium::CreatePeerConnection(
     webrtc::PeerConnectionObserver* observer, PeerConnectionCallback callback) {
   auto& env = MediumEnvironment::Instance();

cpp/platform/impl/g3/webrtc.h

@@ -38,6 +38,8 @@ class WebRtcMedium : public api::WebRtcMedium {
   WebRtcMedium() = default;
   ~WebRtcMedium() override = default;
 
+  const std::string GetDefaultCountryCode() override;
+
   // Creates and returns a new webrtc::PeerConnectionInterface object via
   // |callback|.
   void CreatePeerConnection(webrtc::PeerConnectionObserver* observer,