Remove mutable from rtc::CriticalSection members.

webrtc/system_wrappers/source/clock.cc

 /*
  *  Copyright (c) 2013 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 161 matching lines @@
       ref.counter_ms.QuadPart = timeGetTime();
       Sleep(0);
     } while ((ft0.dwHighDateTime == ft1.dwHighDateTime) &&
              (ft0.dwLowDateTime == ft1.dwLowDateTime));
     ref.file_time = ft1;
     timeEndPeriod(1);
     return ref;
   }
 
   // mutable as time-accessing functions are const.
-  mutable rtc::CriticalSection crit_;
+  rtc::CriticalSection crit_;
   mutable DWORD last_time_ms_;
   mutable LONG num_timer_wraps_;
   const ReferencePoint ref_point_;
 };
 
 #elif ((defined WEBRTC_LINUX) || (defined WEBRTC_MAC))
 class UnixRealTimeClock : public RealTimeClock {
  public:
   UnixRealTimeClock() {}
 
@@ skipping 69 matching lines @@
 void SimulatedClock::AdvanceTimeMilliseconds(int64_t milliseconds) {
   AdvanceTimeMicroseconds(1000 * milliseconds);
 }
 
 void SimulatedClock::AdvanceTimeMicroseconds(int64_t microseconds) {
   WriteLockScoped synchronize(*lock_);
   time_us_ += microseconds;
 }
 
 };  // namespace webrtc