Remove the VoiceEngineObserver callback interface.

voice_engine/voe_base_impl.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.
  */
 
 #ifndef VOICE_ENGINE_VOE_BASE_IMPL_H_
 #define VOICE_ENGINE_VOE_BASE_IMPL_H_
 
 #include "voice_engine/include/voe_base.h"
 
 #include "modules/include/module_common_types.h"
 #include "rtc_base/criticalsection.h"
 #include "voice_engine/shared_data.h"
 
 namespace webrtc {
 
 class ProcessThread;
 
 class VoEBaseImpl : public VoEBase,
                     public AudioTransport,
                     public AudioDeviceObserver {
  public:
-  int RegisterVoiceEngineObserver(VoiceEngineObserver& observer) override;
-  int DeRegisterVoiceEngineObserver() override;
-
   int Init(
       AudioDeviceModule* external_adm,
       AudioProcessing* audio_processing,
       const rtc::scoped_refptr<AudioDecoderFactory>& decoder_factory) override;
   AudioDeviceModule* audio_device_module() override {
     return shared_->audio_device();
   }
   voe::TransmitMixer* transmit_mixer() override {
     return shared_->transmit_mixer();
   }
@@ skipping 59 matching lines @@
   int32_t TerminateInternal();
 
   void GetPlayoutData(int sample_rate, size_t number_of_channels,
                       size_t number_of_frames, bool feed_data_to_apm,
                       void* audio_data, int64_t* elapsed_time_ms,
                       int64_t* ntp_time_ms);
 
   // Initialize channel by setting Engine Information then initializing
   // channel.
   int InitializeChannel(voe::ChannelOwner* channel_owner);
-  VoiceEngineObserver* voiceEngineObserverPtr_;
   rtc::CriticalSection callbackCritSect_;
   rtc::scoped_refptr<AudioDecoderFactory> decoder_factory_;
 
   AudioFrame audioFrame_;
   voe::SharedData* shared_;
 };
 
 }  // namespace webrtc
 
 #endif  // VOICE_ENGINE_VOE_BASE_IMPL_H_