Fix Chromium clang plugin warnings

webrtc/modules/audio_coding/test/utility.h

Index: webrtc/modules/audio_coding/test/utility.h
diff --git a/webrtc/modules/audio_coding/test/utility.h b/webrtc/modules/audio_coding/test/utility.h
index 23869be7ed6497768bcf39f495958c505eeb9718..dbd398ee7dafff31b65d60fc86a3c94bc409c0ec 100644
--- a/webrtc/modules/audio_coding/test/utility.h
+++ b/webrtc/modules/audio_coding/test/utility.h
@@ -118,10 +118,8 @@ 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();