Fix all -Wnon-virtual-dtor warnings.

webrtc/api/webrtcsession_unittest.cc

 /*
  *  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 140 matching lines @@
 enum RTCCertificateGenerationMethod { ALREADY_GENERATED, DTLS_IDENTITY_STORE };
 
 class MockIceObserver : public webrtc::IceObserver {
  public:
   MockIceObserver()
       : oncandidatesready_(false),
         ice_connection_state_(PeerConnectionInterface::kIceConnectionNew),
         ice_gathering_state_(PeerConnectionInterface::kIceGatheringNew) {
   }
 
+  virtual ~MockIceObserver() = default;
+
   void OnIceConnectionChange(
       PeerConnectionInterface::IceConnectionState new_state) override {
     ice_connection_state_ = new_state;
   }
   void OnIceGatheringChange(
       PeerConnectionInterface::IceGatheringState new_state) override {
     // We can never transition back to "new".
     EXPECT_NE(PeerConnectionInterface::kIceGatheringNew, new_state);
     ice_gathering_state_ = new_state;
     oncandidatesready_ =
@@ skipping 4235 matching lines @@
 }
 
 // TODO(bemasc): Add a TestIceStatesBundle with BUNDLE enabled.  That test
 // currently fails because upon disconnection and reconnection OnIceComplete is
 // called more than once without returning to IceGatheringGathering.
 
 INSTANTIATE_TEST_CASE_P(WebRtcSessionTests,
                         WebRtcSessionTest,
                         testing::Values(ALREADY_GENERATED,
                                         DTLS_IDENTITY_STORE));