Remove CriticalSectionWrapper from audio conference mixer.

webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.h

Index: webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.h
diff --git a/webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.h b/webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.h
index c2fbe98fa09ce9c5d6f86e4b62377a5e68111e13..e5065a4b56916e75017fb9078913f62f2b8d7195 100644
--- a/webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.h
+++ b/webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.h
@@ -15,6 +15,7 @@
 #include <map>
 #include <memory>
 
+#include "webrtc/base/criticalsection.h"
 #include "webrtc/modules/audio_conference_mixer/include/audio_conference_mixer.h"
 #include "webrtc/modules/audio_conference_mixer/source/memory_pool.h"
 #include "webrtc/modules/audio_conference_mixer/source/time_scheduler.h"
@@ -23,7 +24,6 @@
 
 namespace webrtc {
 class AudioProcessing;
-class CriticalSectionWrapper;
 
 struct FrameAndMuteInfo {
   FrameAndMuteInfo(AudioFrame* f, bool m) : frame(f), muted(m) {}
@@ -148,8 +148,8 @@ private:
 
     bool LimitMixedAudio(AudioFrame* mixedAudio) const;
 
-    std::unique_ptr<CriticalSectionWrapper> _crit;
-    std::unique_ptr<CriticalSectionWrapper> _cbCrit;
+    const rtc::CriticalSection _crit;
+    const rtc::CriticalSection _cbCrit;
 
     int32_t _id;