Remove mutable from rtc::CriticalSections.

webrtc/video/payload_router.h

 /*
  *  Copyright (c) 2015 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 51 matching lines @@
   // Returns the maximum allowed data payload length, given the configured MTU
   // and RTP headers.
   size_t MaxPayloadLength() const;
 
   void AddRef() { ++ref_count_; }
   void Release() { if (--ref_count_ == 0) { delete this; } }
 
  private:
   // TODO(mflodman): When the new video API has launched, remove crit_ and
   // assume rtp_modules_ will never change during a call.
-  mutable rtc::CriticalSection crit_;
+  rtc::CriticalSection crit_;
 
   // Active sending RTP modules, in layer order.
   std::vector<RtpRtcp*> rtp_modules_ GUARDED_BY(crit_);
   bool active_ GUARDED_BY(crit_);
 
   Atomic32 ref_count_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(PayloadRouter);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_PAYLOAD_ROUTER_H_