Remove mutable from rtc::CriticalSections.

webrtc/voice_engine/channel_manager.h

 /*
  *  Copyright (c) 2011 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 105 matching lines @@
   RtcEventLog* GetEventLog() const;
 
  private:
   // Create a channel given a configuration, |config|.
   ChannelOwner CreateChannelInternal(const Config& config);
 
   uint32_t instance_id_;
 
   Atomic32 last_channel_id_;
 
-  mutable rtc::CriticalSection lock_;
+  rtc::CriticalSection lock_;
   std::vector<ChannelOwner> channels_;
 
   const Config& config_;
   rtc::scoped_ptr<RtcEventLog> event_log_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(ChannelManager);
 };
 }  // namespace voe
 }  // namespace webrtc
 
 #endif  // WEBRTC_VOICE_ENGINE_CHANNEL_MANAGER_H