Update thread annotiation macros in rtc_base to use RTC_ prefix

webrtc/rtc_base/rate_limiter.h

 /*
  *  Copyright (c) 2016 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 26 matching lines @@
   void SetMaxRate(uint32_t max_rate_bps);
 
   // Set the window size over which to measure the current bitrate.
   // For example, irt retransmissions, this is typically the RTT.
   // Returns true on success and false if window_size_ms is out of range.
   bool SetWindowSize(int64_t window_size_ms);
 
  private:
   const Clock* const clock_;
   rtc::CriticalSection lock_;
-  RateStatistics current_rate_ GUARDED_BY(lock_);
-  int64_t window_size_ms_ GUARDED_BY(lock_);
-  uint32_t max_rate_bps_ GUARDED_BY(lock_);
+  RateStatistics current_rate_ RTC_GUARDED_BY(lock_);
+  int64_t window_size_ms_ RTC_GUARDED_BY(lock_);
+  uint32_t max_rate_bps_ RTC_GUARDED_BY(lock_);
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(RateLimiter);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_RTC_BASE_RATE_LIMITER_H_