Remove AudioDeviceObserver and make ADM not inherit from the Module interface.

modules/audio_device/linux/audio_device_pulse_linux.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 169 matching lines @@
     int32_t SetStereoPlayout(bool enable) override;
     int32_t StereoPlayout(bool& enabled) const override;
     int32_t StereoRecordingIsAvailable(bool& available) override;
     int32_t SetStereoRecording(bool enable) override;
     int32_t StereoRecording(bool& enabled) const override;
 
     // Delay information and control
     int32_t PlayoutDelay(uint16_t& delayMS) const override;
     int32_t RecordingDelay(uint16_t& delayMS) const override;
 
-    bool PlayoutWarning() const override;
-    bool PlayoutError() const override;
-    bool RecordingWarning() const override;
-    bool RecordingError() const override;
-    void ClearPlayoutWarning() override;
-    void ClearPlayoutError() override;
-    void ClearRecordingWarning() override;
-    void ClearRecordingError() override;
-
    void AttachAudioBuffer(AudioDeviceBuffer* audioBuffer) override;
 
 private:
  void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION(_critSect) { _critSect.Enter(); }
  void UnLock() RTC_UNLOCK_FUNCTION(_critSect) { _critSect.Leave(); }
  void WaitForOperationCompletion(pa_operation* paOperation) const;
  void WaitForSuccess(pa_operation* paOperation) const;
 
  bool KeyPressed() const;
 
@@ skipping 90 matching lines @@
  bool _stopRec;
  bool _startPlay;
  bool _stopPlay;
  bool _AGC;
  bool update_speaker_volume_at_startup_;
 
  uint32_t _sndCardPlayDelay;
  uint32_t _sndCardRecDelay;
 
  int32_t _writeErrors;
- uint16_t _playWarning;
- uint16_t _playError;
- uint16_t _recWarning;
- uint16_t _recError;
 
  uint16_t _deviceIndex;
  int16_t _numPlayDevices;
  int16_t _numRecDevices;
  char* _playDeviceName;
  char* _recDeviceName;
  char* _playDisplayDeviceName;
  char* _recDisplayDeviceName;
  char _paServerVersion[32];
 
@@ skipping 24 matching lines @@
  pa_buffer_attr _playBufferAttr;
  pa_buffer_attr _recBufferAttr;
 
  char _oldKeyState[32];
  Display* _XDisplay;
 };
 
 }
 
 #endif  // MODULES_AUDIO_DEVICE_MAIN_SOURCE_LINUX_AUDIO_DEVICE_PULSE_LINUX_H_