Remove mutable from rtc::CriticalSection members.

webrtc/modules/bitrate_controller/bitrate_controller_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.
  *
  *  Usage: this class will register multiple RtcpBitrateObserver's one at each
@@ skipping 56 matching lines @@
 
   void OnNetworkChanged(uint32_t bitrate,
                         uint8_t fraction_loss,  // 0 - 255.
                         int64_t rtt) EXCLUSIVE_LOCKS_REQUIRED(critsect_);
 
   // Used by process thread.
   Clock* clock_;
   BitrateObserver* observer_;
   int64_t last_bitrate_update_ms_;
 
-  mutable rtc::CriticalSection critsect_;
+  rtc::CriticalSection critsect_;
   SendSideBandwidthEstimation bandwidth_estimation_ GUARDED_BY(critsect_);
   uint32_t reserved_bitrate_bps_ GUARDED_BY(critsect_);
 
   uint32_t last_bitrate_bps_ GUARDED_BY(critsect_);
   uint8_t last_fraction_loss_ GUARDED_BY(critsect_);
   int64_t last_rtt_ms_ GUARDED_BY(critsect_);
   uint32_t last_reserved_bitrate_bps_ GUARDED_BY(critsect_);
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(BitrateControllerImpl);
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_BITRATE_CONTROLLER_BITRATE_CONTROLLER_IMPL_H_