Fix Chromium clang plugin warnings

webrtc/modules/audio_coding/test/Channel.h

 /*
  *  Copyright (c) 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 29 matching lines @@
   int16_t payloadType;
   size_t lastPayloadLenByte;
   uint32_t lastTimestamp;
   ACMTestFrameSizeStats frameSizeStats[MAX_NUM_FRAMESIZES];
 };
 
 class Channel : public AudioPacketizationCallback {
  public:
 
   Channel(int16_t chID = -1);
-  ~Channel();
+  ~Channel() override;
 
   int32_t SendData(FrameType frameType,
                    uint8_t payloadType,
                    uint32_t timeStamp,
                    const uint8_t* payloadData,
                    size_t payloadSize,
                    const RTPFragmentationHeader* fragmentation) override;
 
   void RegisterReceiverACM(AudioCodingModule *acm);
 
@@ skipping 59 matching lines @@
   // External timing info, defaulted to -1. Only used if they are
   // non-negative.
   int64_t external_send_timestamp_;
   int32_t external_sequence_number_;
   int num_packets_to_drop_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_TEST_CHANNEL_H_