Fix segfault when PeerConnection is destroyed during stats collection.

webrtc/api/rtcstats_integrationtest.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 519 matching lines @@
   RTCStatsReportVerifier(report.get()).VerifyReport();
 }
 
 TEST_F(RTCStatsIntegrationTest, GetStatsFromCallee) {
   StartCall();
 
   rtc::scoped_refptr<const RTCStatsReport> report = GetStatsFromCallee();
   RTCStatsReportVerifier(report.get()).VerifyReport();
 }
 
+TEST_F(RTCStatsIntegrationTest, GetsStatsWhileDestroyingPeerConnections) {
+  StartCall();
+
+  rtc::scoped_refptr<RTCStatsObtainer> stats_obtainer =
+      RTCStatsObtainer::Create();
+  caller_->pc()->GetStats(stats_obtainer);
+  // This will destroy the peer connection.
+  caller_ = nullptr;
+  // Any pending stats requests should have completed in the act of destroying
+  // the peer connection.
+  EXPECT_TRUE(stats_obtainer->report());
+}
+
 }  // namespace
 
 }  // namespace webrtc