Regression test for issue where Opus DTX status was being forgotten.

webrtc/voice_engine/channel.cc

Index: webrtc/voice_engine/channel.cc
diff --git a/webrtc/voice_engine/channel.cc b/webrtc/voice_engine/channel.cc
index 424d291bcbb3a274dd5ce4a302bd014dad7bc5f4..75dc459fc0caa00985736432af74b899430eb204 100644
--- a/webrtc/voice_engine/channel.cc
+++ b/webrtc/voice_engine/channel.cc
@@ -1548,6 +1548,10 @@ int Channel::SetOpusDtx(bool enable_dtx) {
   return 0;
 }
 
+int Channel::GetOpusDtx(bool* enabled) {
+  return audio_coding_->GetOpusDtx(enabled);
+}
+
 int32_t Channel::RegisterExternalTransport(Transport* transport) {
   WEBRTC_TRACE(kTraceInfo, kTraceVoice, VoEId(_instanceId, _channelId),
                "Channel::RegisterExternalTransport()");