Fix Chromium clang plugin warnings

webrtc/modules/audio_coding/acm2/acm_receive_test_oldapi.cc

 /*
  *  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 94 matching lines @@
     int output_freq_hz,
     NumOutputChannels exptected_output_channels)
     : clock_(0),
       acm_(webrtc::AudioCodingModule::Create(0, &clock_)),
       packet_source_(packet_source),
       audio_sink_(audio_sink),
       output_freq_hz_(output_freq_hz),
       exptected_output_channels_(exptected_output_channels) {
 }
 
+AcmReceiveTestOldApi::~AcmReceiveTestOldApi() = default;
+
 void AcmReceiveTestOldApi::RegisterDefaultCodecs() {
   CodecInst my_codec_param;
   for (int n = 0; n < acm_->NumberOfCodecs(); n++) {
     ASSERT_EQ(0, acm_->Codec(n, &my_codec_param)) << "Failed to get codec.";
     if (ModifyAndUseThisCodec(&my_codec_param)) {
       ASSERT_EQ(0, acm_->RegisterReceiveCodec(my_codec_param))
           << "Couldn't register receive codec.\n";
     }
   }
 }
@@ skipping 93 matching lines @@
   if (clock_.TimeInMilliseconds() >= last_toggle_time_ms_ + toggle_period_ms_) {
     output_freq_hz_ = (output_freq_hz_ == output_freq_hz_1_)
                           ? output_freq_hz_2_
                           : output_freq_hz_1_;
     last_toggle_time_ms_ = clock_.TimeInMilliseconds();
   }
 }
 
 }  // namespace test
 }  // namespace webrtc