Convert CNG into C++ and remove it from AudioDecoder

webrtc/modules/audio_coding/neteq/audio_decoder_impl.cc

Index: webrtc/modules/audio_coding/neteq/audio_decoder_impl.cc
diff --git a/webrtc/modules/audio_coding/neteq/audio_decoder_impl.cc b/webrtc/modules/audio_coding/neteq/audio_decoder_impl.cc
index d800cc7dbe939b48dcb429b2b47622be29132963..a9d6cc156463faffdc3f04f30ac66e31d7852eed 100644
--- a/webrtc/modules/audio_coding/neteq/audio_decoder_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/audio_decoder_impl.cc
@@ -36,43 +36,6 @@
 
 namespace webrtc {
 
-AudioDecoderCng::AudioDecoderCng() {
-  RTC_CHECK_EQ(0, WebRtcCng_CreateDec(&dec_state_));
-  WebRtcCng_InitDec(dec_state_);
-}
-
-AudioDecoderCng::~AudioDecoderCng() {
-  WebRtcCng_FreeDec(dec_state_);
-}
-
-void AudioDecoderCng::Reset() {
-  WebRtcCng_InitDec(dec_state_);
-}
-
-int AudioDecoderCng::IncomingPacket(const uint8_t* payload,
-                                    size_t payload_len,
-                                    uint16_t rtp_sequence_number,
-                                    uint32_t rtp_timestamp,
-                                    uint32_t arrival_timestamp) {
-  return -1;
-}
-
-CNG_dec_inst* AudioDecoderCng::CngDecoderInstance() {
-  return dec_state_;
-}
-
-size_t AudioDecoderCng::Channels() const {
-  return 1;
-}
-
-int AudioDecoderCng::DecodeInternal(const uint8_t* encoded,
-                                    size_t encoded_len,
-                                    int sample_rate_hz,
-                                    int16_t* decoded,
-                                    SpeechType* speech_type) {
-  return -1;
-}
-
 bool CodecSupported(NetEqDecoder codec_type) {
   switch (codec_type) {
     case NetEqDecoder::kDecoderPCMu:
@@ -228,7 +191,7 @@ AudioDecoder* CreateAudioDecoder(NetEqDecoder codec_type) {
     case NetEqDecoder::kDecoderCNGwb:
     case NetEqDecoder::kDecoderCNGswb32kHz:
     case NetEqDecoder::kDecoderCNGswb48kHz:
-      return new AudioDecoderCng;
+      RTC_CHECK(false && "CNG should not be created like this right now!");

[kwiberg-webrtc, 2016/04/09 07:34:49]

RTC_CHECK(false) << "CNG should not be created like this right now!";

[ossu, 2016/04/11 08:31:10]

Acknowledged.

[hlundin-webrtc, 2016/04/11 11:33:00]

I guess RTC_NOTREACHED() is yet another way to say it.

I think you should drop the "right now", since I think we want to keep CNG
outside of the AudioDecoder interface.

[kwiberg-webrtc, 2016/04/11 12:42:56]

Yes, but bear in mind that that one uses DCHECK, not CHECK. (Hmm. Perhaps it
ought to use CHECK instead? Since the line should never be reached, there won't
be any overhead... hmm... except that the compiler could optimize based on our
assertion... need to think more about this.)

[ossu, 2016/04/11 12:59:57]

It makes sense that NOTREACHED should be in even in release builds. As you say,
since it should _never_ happen, its cost (except in code size) shouldn't matter.
I'll keep it as RTC_CHECK(false) until this is resolved, though.

[ossu, 2016/04/11 12:59:57]

Acknowledged.

[kwiberg-webrtc, 2016/04/11 13:28:26]

Yes. Except that the compiler can optimize the surrounding code based on our
assertion that this statement can't be reached.
Good.

     case NetEqDecoder::kDecoderRED:
     case NetEqDecoder::kDecoderAVT:
     case NetEqDecoder::kDecoderArbitrary: