RTCStatsReport::AddStats DCHECKs that the ID is unique.

webrtc/stats/rtcstatsreport.cc

 /*
  *  Copyright 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 51 matching lines @@
       new rtc::RefCountedObject<RTCStatsReport>(timestamp_us));
 }
 
 RTCStatsReport::RTCStatsReport(int64_t timestamp_us)
     : timestamp_us_(timestamp_us) {
 }
 
 RTCStatsReport::~RTCStatsReport() {
 }
 
-bool RTCStatsReport::AddStats(std::unique_ptr<const RTCStats> stats) {
-  return !stats_.insert(std::make_pair(std::string(stats->id()),
-                        std::move(stats))).second;
+void RTCStatsReport::AddStats(std::unique_ptr<const RTCStats> stats) {
+  auto result = stats_.insert(std::make_pair(std::string(stats->id()),
+                              std::move(stats)));
+  RTC_DCHECK(result.second) <<
+      "A stats object with ID " << result.first->second->id() << " is already "
+      "present in this stats report.";
 }
 
 const RTCStats* RTCStatsReport::Get(const std::string& id) const {
   StatsMap::const_iterator it = stats_.find(id);
   if (it != stats_.cend())
     return it->second.get();
   return nullptr;
 }
 
 void RTCStatsReport::TakeMembersFrom(
@@ skipping 21 matching lines @@
   if (it != end()) {
     oss << it->ToString();
     for (++it; it != end(); ++it) {
       oss << '\n' << it->ToString();
     }
   }
   return oss.str();
 }
 
 }  // namespace webrtc