Remove the preprocessor symbol WEBRTC_CODEC_PCM16 (it was always defined)

webrtc/modules/audio_coding/neteq/audio_decoder_impl.h

 /*
  *  Copyright (c) 2012 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 75 matching lines @@
       : AudioDecoderPcmA(), channels_(channels) {
     assert(channels > 0);
   }
   size_t Channels() const override;
 
  private:
   const size_t channels_;
   DISALLOW_COPY_AND_ASSIGN(AudioDecoderPcmAMultiCh);
 };
 
-#ifdef WEBRTC_CODEC_PCM16
 // This class handles all four types (i.e., sample rates) of PCM16B codecs.
 // The type is specified in the constructor parameter |type|.
 class AudioDecoderPcm16B : public AudioDecoder {
  public:
   AudioDecoderPcm16B();
   void Reset() override;
   int PacketDuration(const uint8_t* encoded, size_t encoded_len) const override;
   size_t Channels() const override;
 
  protected:
@@ skipping 12 matching lines @@
 // of channels is derived from the type.
 class AudioDecoderPcm16BMultiCh : public AudioDecoderPcm16B {
  public:
   explicit AudioDecoderPcm16BMultiCh(size_t num_channels);
   size_t Channels() const override;
 
  private:
   const size_t channels_;
   DISALLOW_COPY_AND_ASSIGN(AudioDecoderPcm16BMultiCh);
 };
-#endif
 
 #ifdef WEBRTC_CODEC_ILBC
 class AudioDecoderIlbc : public AudioDecoder {
  public:
   AudioDecoderIlbc();
   ~AudioDecoderIlbc() override;
   bool HasDecodePlc() const override;
   size_t DecodePlc(size_t num_frames, int16_t* decoded) override;
   void Reset() override;
   size_t Channels() const override;
@@ skipping 132 matching lines @@
 // Returns the sample rate for |codec_type|.
 int CodecSampleRateHz(NetEqDecoder codec_type);
 
 // Creates an AudioDecoder object of type |codec_type|. Returns NULL for for
 // unsupported codecs, and when creating an AudioDecoder is not applicable
 // (e.g., for RED and DTMF/AVT types).
 AudioDecoder* CreateAudioDecoder(NetEqDecoder codec_type);
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_AUDIO_DECODER_IMPL_H_