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

modules/audio_device/mac/audio_device_mac.h

Index: modules/audio_device/mac/audio_device_mac.h
diff --git a/modules/audio_device/mac/audio_device_mac.h b/modules/audio_device/mac/audio_device_mac.h
index db8cfea50e41e94d51ff7b1b99b6d494c905ad8a..c72b741bafca7d97f7ff7ae478b072b1cc3b0037 100644
--- a/modules/audio_device/mac/audio_device_mac.h
+++ b/modules/audio_device/mac/audio_device_mac.h
@@ -153,15 +153,6 @@ class AudioDeviceMac : public AudioDeviceGeneric {
   virtual int32_t PlayoutDelay(uint16_t& delayMS) const;
   virtual int32_t RecordingDelay(uint16_t& delayMS) const;
 
-  virtual bool PlayoutWarning() const;
-  virtual bool PlayoutError() const;
-  virtual bool RecordingWarning() const;
-  virtual bool RecordingError() const;
-  virtual void ClearPlayoutWarning();
-  virtual void ClearPlayoutError();
-  virtual void ClearRecordingWarning();
-  virtual void ClearRecordingError();
-
   virtual void AttachAudioBuffer(AudioDeviceBuffer* audioBuffer);
 
  private:
@@ -333,11 +324,6 @@ class AudioDeviceMac : public AudioDeviceGeneric {
 
   int32_t _renderDelayOffsetSamples;
 
-  uint16_t _playWarning;
-  uint16_t _playError;
-  uint16_t _recWarning;
-  uint16_t _recError;
-
   PaUtilRingBuffer* _paCaptureBuffer;
   PaUtilRingBuffer* _paRenderBuffer;