Make an enum class out of NetEqDecoder, and hide the neteq_decoders_ table

webrtc/modules/audio_coding/main/acm2/acm_codec_database.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 83 matching lines @@
   // Databases with information about the supported codecs
   // database_ - stored information about all codecs: payload type, name,
   //             sampling frequency, packet size in samples, default channel
   //             support, and default rate.
   // codec_settings_ - stored codec settings: number of allowed packet sizes,
   //                   a vector with the allowed packet sizes, basic block
   //                   samples, and max number of channels that are supported.
   // neteq_decoders_ - list of supported decoders in NetEQ.
   static const CodecInst database_[kMaxNumCodecs];
   static const CodecSettings codec_settings_[kMaxNumCodecs];
+
+ private:
   static const NetEqDecoder neteq_decoders_[kMaxNumCodecs];
+
+  friend class RentACodec;
 };
 
 }  // namespace acm2
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_MAIN_ACM2_ACM_CODEC_DATABASE_H_