Remove the VoiceEngineObserver callback interface.

voice_engine/monitor_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.
- */
-
-#ifndef VOICE_ENGINE_MONITOR_MODULE_H_
-#define VOICE_ENGINE_MONITOR_MODULE_H_
-
-#include "modules/include/module.h"
-
-namespace webrtc {
-namespace voe {
-
-// When associated with a ProcessThread, calls a callback method
-// |OnPeriodicProcess()| implemented by the |Observer|.
-// TODO(tommi): This could be replaced with PostDelayedTask().
-// Better yet, delete it and delete code related to |_saturationWarning|
-// in TransmitMixer (and the OnPeriodicProcess callback).
-template <typename Observer>
-class MonitorModule : public Module {
- public:
-  explicit MonitorModule(Observer* observer) : observer_(observer) {}
-  ~MonitorModule() override {}
-
- private:
-  int64_t TimeUntilNextProcess() override { return 1000; }
-  void Process() override { observer_->OnPeriodicProcess(); }
-
-  Observer* const observer_;
-};
-
-}  // namespace voe
-}  // namespace webrtc
-
-#endif  // VOICE_ENGINE_MONITOR_MODULE