Fix Chromium clang plugin warnings

webrtc/modules/audio_coding/acm2/acm_send_test_oldapi.h

 /*
  *  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.
  */
 
@@ skipping 14 matching lines @@
 namespace test {
 class InputAudioFile;
 class Packet;
 
 class AcmSendTestOldApi : public AudioPacketizationCallback,
                           public PacketSource {
  public:
   AcmSendTestOldApi(InputAudioFile* audio_source,
                     int source_rate_hz,
                     int test_duration_ms);
-  virtual ~AcmSendTestOldApi() {}
+  ~AcmSendTestOldApi() override;
 
   // Registers the send codec. Returns true on success, false otherwise.
   bool RegisterCodec(const char* payload_name,
                      int sampling_freq_hz,
                      int channels,
                      int payload_type,
                      int frame_size_samples);
 
   // Registers an external send codec. Returns true on success, false otherwise.
   bool RegisterExternalCodec(AudioEncoder* external_speech_encoder);
@@ skipping 33 matching lines @@
   uint16_t sequence_number_;
   std::vector<uint8_t> last_payload_vec_;
   bool data_to_send_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(AcmSendTestOldApi);
 };
 
 }  // namespace test
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_ACM2_ACM_SEND_TEST_OLDAPI_H_