Turn webrtc::Vad into a pure virtual interface

webrtc/modules/audio_coding/codecs/cng/audio_encoder_cng.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 36 matching lines @@
     return false;
   return true;
 }
 
 AudioEncoderCng::AudioEncoderCng(const Config& config)
     : speech_encoder_(config.speech_encoder),
       cng_payload_type_(config.payload_type),
       num_cng_coefficients_(config.num_cng_coefficients),
       sid_frame_interval_ms_(config.sid_frame_interval_ms),
       last_frame_active_(true),
-      vad_(config.vad ? config.vad : new Vad(config.vad_mode)) {
+      vad_(config.vad ? rtc_make_scoped_ptr(config.vad)
+                      : CreateVad(config.vad_mode)) {
   CHECK(config.IsOk()) << "Invalid configuration.";
   cng_inst_ = CreateCngInst(SampleRateHz(), sid_frame_interval_ms_,
                             num_cng_coefficients_);
 }
 
 AudioEncoderCng::~AudioEncoderCng() = default;
 
 size_t AudioEncoderCng::MaxEncodedBytes() const {
   const size_t max_encoded_bytes_active = speech_encoder_->MaxEncodedBytes();
   const size_t max_encoded_bytes_passive =
@@ skipping 188 matching lines @@
     }
   }
   return info;
 }
 
 size_t AudioEncoderCng::SamplesPer10msFrame() const {
   return rtc::CheckedDivExact(10 * SampleRateHz(), 1000);
 }
 
 }  // namespace webrtc