Remove no-op and unused methods from AudioCodingModule

webrtc/modules/audio_coding/main/test/TestVADDTX.h

 /*
  *  Copyright (c) 2011 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 70 matching lines @@
 
   void Perform() override;
 
  private:
   void RunTestCases();
   void Test(bool new_outfile);
   void SetVAD(bool enable_dtx, bool enable_vad, ACMVADMode vad_mode);
 
   bool vad_enabled_;
   bool dtx_enabled_;
-  bool use_webrtc_dtx_;
   int output_file_num_;
 };
 
 // TestOpusDtx is to verify that the Opus DTX performs as it should.
 class TestOpusDtx final : public TestVadDtx {
  public:
   void Perform() override;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_MAIN_TEST_TESTVADDTX_H_