Replace NULL with nullptr or null in webrtc/api/.

webrtc/api/statstypes.h

 /*
  *  Copyright 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.
  */
 
@@ skipping 397 matching lines @@
   const_iterator begin() const;
   const_iterator end() const;
   size_t size() const;
 
   // Creates a new report object with |id| that does not already
   // exist in the list of reports.
   StatsReport* InsertNew(const StatsReport::Id& id);
   StatsReport* FindOrAddNew(const StatsReport::Id& id);
   StatsReport* ReplaceOrAddNew(const StatsReport::Id& id);
 
-  // Looks for a report with the given |id|.  If one is not found, NULL
+  // Looks for a report with the given |id|.  If one is not found, null
   // will be returned.
   StatsReport* Find(const StatsReport::Id& id);
 
  private:
   Container list_;
   rtc::ThreadChecker thread_checker_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_STATSTYPES_H_