Update thread annotiation macros to use RTC_ prefix

webrtc/system_wrappers/source/metrics_default.cc

 // Copyright (c) 2014 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.
 //
 
 #include "webrtc/system_wrappers/include/metrics_default.h"
@@ skipping 75 matching lines @@
 
   int MinSample() const {
     rtc::CritScope cs(&crit_);
     return (info_.samples.empty()) ? -1 : info_.samples.begin()->first;
   }
 
  private:
   rtc::CriticalSection crit_;
   const int min_;
   const int max_;
-  SampleInfo info_ GUARDED_BY(crit_);
+  SampleInfo info_ RTC_GUARDED_BY(crit_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(RtcHistogram);
 };
 
 class RtcHistogramMap {
  public:
   RtcHistogramMap() {}
   ~RtcHistogramMap() {}
 
   Histogram* GetCountsHistogram(const std::string& name,
@@ skipping 51 matching lines @@
   }
 
   int MinSample(const std::string& name) const {
     rtc::CritScope cs(&crit_);
     const auto& it = map_.find(name);
     return (it == map_.end()) ? -1 : it->second->MinSample();
   }
 
  private:
   rtc::CriticalSection crit_;
-  std::map<std::string, std::unique_ptr<RtcHistogram>> map_ GUARDED_BY(crit_);
+  std::map<std::string, std::unique_ptr<RtcHistogram>> map_
+      RTC_GUARDED_BY(crit_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(RtcHistogramMap);
 };
 
 // RtcHistogramMap is allocated upon call to Enable().
 // The histogram getter functions, which return pointer values to the histograms
 // in the map, are cached in WebRTC. Therefore, this memory is not freed by the
 // application (the memory will be reclaimed by the OS).
 static RtcHistogramMap* volatile g_rtc_histogram_map = nullptr;
 
@@ skipping 119 matching lines @@
   return map ? map->NumSamples(name) : 0;
 }
 
 int MinSample(const std::string& name) {
   RtcHistogramMap* map = GetMap();
   return map ? map->MinSample(name) : -1;
 }
 
 }  // namespace metrics
 }  // namespace webrtc