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

webrtc/modules/audio_coding/include/audio_coding_module.h

 /*
  *  Copyright (c) 2012 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 748 matching lines @@
   // int DisableOpusDtx()
   // If current send codec is Opus, disables its internal DTX.
   //
   // Return value:
   //   -1 if current send codec is not Opus or error occurred in disabling DTX.
   //    0 if Opus DTX is disabled successfully.
   //
   virtual int DisableOpusDtx() = 0;
 
   ///////////////////////////////////////////////////////////////////////////
+  // int GetOpusDtx()

[minyue-webrtc, 2016/07/25 16:13:01]

I think we can avoid introducing this function by using

ModifyEncoder() in the test code itself. I think that we are moving away from
using ACM as relay on requests like this.

It would be even better if we add QueryEncoder() in analogy to ModifyEncoder(),
but allows it to call const methods of AudioEncoder. If this is irrelevant of
this CL, consider using ModifyEncoder() and add a TODO.

[ivoc, 2016/07/25 17:11:09]

Good point, that is indeed a better approach. I added a QueryEncoder function
like you suggested.

+  // If current send codec is Opus, get the status of its internal DTX.
+  //
+  // Return value:
+  //   -1 if current send codec is not Opus.
+  //    0 if the Opus DTX status is written to |enabled| successfully.
+  //
+  virtual int GetOpusDtx(bool* enabled) = 0;
+
+  ///////////////////////////////////////////////////////////////////////////
   //   statistics
   //
 
   ///////////////////////////////////////////////////////////////////////////
   // int32_t  GetNetworkStatistics()
   // Get network statistics. Note that the internal statistics of NetEq are
   // reset by this call.
   //
   // Input:
   //   -network_statistics : a structure that contains network statistics.
@@ skipping 33 matching lines @@
   virtual std::vector<uint16_t> GetNackList(
       int64_t round_trip_time_ms) const = 0;
 
   virtual void GetDecodingCallStatistics(
       AudioDecodingCallStats* call_stats) const = 0;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_INCLUDE_AUDIO_CODING_MODULE_H_