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

webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 134 matching lines @@
   conf.fec_enabled = enable;
   return RecreateEncoderInstance(conf);
 }
 
 bool AudioEncoderOpus::SetDtx(bool enable) {
   auto conf = config_;
   conf.dtx_enabled = enable;
   return RecreateEncoderInstance(conf);
 }
 
+bool AudioEncoderOpus::GetDtx() const {
+  return config_.dtx_enabled;
+}
+
 bool AudioEncoderOpus::SetApplication(Application application) {
   auto conf = config_;
   switch (application) {
     case Application::kSpeech:
       conf.application = AudioEncoderOpus::kVoip;
       break;
     case Application::kAudio:
       conf.application = AudioEncoderOpus::kAudio;
       break;
   }
@@ skipping 110 matching lines @@
     RTC_CHECK_EQ(0, WebRtcOpus_DisableDtx(inst_));
   }
   RTC_CHECK_EQ(0,
                WebRtcOpus_SetPacketLossRate(
                    inst_, static_cast<int32_t>(packet_loss_rate_ * 100 + .5)));
   config_ = config;
   return true;
 }
 
 }  // namespace webrtc