Fix Chromium clang plugin warnings

webrtc/modules/audio_coding/test/utility.h

 /*
  *  Copyright (c) 2011 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 100 matching lines @@
 
 int16_t ChooseCodec(CodecInst& codecInst);
 
 void PrintCodecs();
 
 bool FixedPayloadTypeCodec(const char* payloadName);
 
 class VADCallback : public ACMVADCallback {
  public:
   VADCallback();
-  ~VADCallback() {
-  }
 
-  int32_t InFrameType(FrameType frame_type);
+  int32_t InFrameType(FrameType frame_type) override;
 
   void PrintFrameTypes();
   void Reset();
 
  private:
   uint32_t _numFrameTypes[5];
 };
 
 void UseLegacyAcm(webrtc::Config* config);
 
 void UseNewAcm(webrtc::Config* config);
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_TEST_UTILITY_H_