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

webrtc/modules/audio_coding/codecs/audio_encoder.h

Index: webrtc/modules/audio_coding/codecs/audio_encoder.h
diff --git a/webrtc/modules/audio_coding/codecs/audio_encoder.h b/webrtc/modules/audio_coding/codecs/audio_encoder.h
index ecc28d96a16239de05e39f04b3f41676f2d3f380..f09525f145d2cc661bf2da00931ac9e2da10f22f 100644
--- a/webrtc/modules/audio_coding/codecs/audio_encoder.h
+++ b/webrtc/modules/audio_coding/codecs/audio_encoder.h
@@ -127,6 +127,10 @@ class AudioEncoder {
   // supported).
   virtual bool SetDtx(bool enable);
 
+  // Returns the status of codec-internal DTX. The default implementation always
+  // returns false.
+  virtual bool GetDtx() const;
+
   // Sets the application mode. Returns true if the codec was able to comply.
   // The default implementation just returns false.
   enum class Application { kSpeech, kAudio };