Lock scheme #8: Introduced the new locking scheme

webrtc/modules/audio_processing/noise_suppression_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 WEBRTC_MODULES_AUDIO_PROCESSING_NOISE_SUPPRESSION_IMPL_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_NOISE_SUPPRESSION_IMPL_H_
 
+#include "webrtc/base/criticalsection.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/modules/audio_processing/processing_component.h"
 
 namespace webrtc {
 
 class AudioBuffer;
-class CriticalSectionWrapper;
 
 class NoiseSuppressionImpl : public NoiseSuppression,
                              public ProcessingComponent {
  public:
   NoiseSuppressionImpl(const AudioProcessing* apm,
-                       CriticalSectionWrapper* crit);
+                       rtc::CriticalSection* crit);
   virtual ~NoiseSuppressionImpl();
 
   int AnalyzeCaptureAudio(AudioBuffer* audio);
   int ProcessCaptureAudio(AudioBuffer* audio);
 
   // NoiseSuppression implementation.
   bool is_enabled() const override;
   float speech_probability() const override;
   Level level() const override;
 
  private:
   // NoiseSuppression implementation.
   int Enable(bool enable) override;
   int set_level(Level level) override;
 
   // ProcessingComponent implementation.
   void* CreateHandle() const override;
   int InitializeHandle(void* handle) const override;
   int ConfigureHandle(void* handle) const override;
   void DestroyHandle(void* handle) const override;
   int num_handles_required() const override;
   int GetHandleError(void* handle) const override;
 
+  // Not guarded as its public API is thread safe.
   const AudioProcessing* apm_;
-  CriticalSectionWrapper* crit_;
-  Level level_;
+
+  rtc::CriticalSection* const crit_;
+
+  Level level_ GUARDED_BY(crit_);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_NOISE_SUPPRESSION_IMPL_H_