Revert of Introduced new scheme for controlling the functionality inside the audio processing module

webrtc/modules/audio_processing/level_controller/level_controller.h

 /*
  *  Copyright (c) 2016 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 20 matching lines @@
 
 class LevelController {
  public:
   LevelController();
   ~LevelController();
 
   void Initialize(int sample_rate_hz);
   void Process(AudioBuffer* audio);
   float GetLastGain() { return last_gain_; }
 
-  // Validates a config.
-  static bool Validate(const AudioProcessing::Config::LevelController& config);
-  // Dumps a config to a string.
-  static std::string ToString(
-      const AudioProcessing::Config::LevelController& config);
-
  private:
   class Metrics {
    public:
     Metrics() { Initialize(AudioProcessing::kSampleRate48kHz); }
     void Initialize(int sample_rate_hz);
     void Update(float long_term_peak_level,
                 float noise_level,
                 float gain,
                 float frame_peak_level);
 
@@ skipping 23 matching lines @@
   float dc_level_[2];
   float dc_forgetting_factor_;
   float last_gain_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(LevelController);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_LEVEL_CONTROLLER_LEVEL_CONTROLLER_H_