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

webrtc/modules/audio_coding/neteq/neteq_network_stats_unittest.cc

 /*
  *  Copyright (c) 2015 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 256 matching lines @@
   rtc::scoped_ptr<test::RtpGenerator> rtp_generator_;
   WebRtcRTPHeader rtp_header_;
   uint32_t last_lost_time_;
   uint32_t packet_loss_interval_;
   uint8_t payload_[kPayloadSizeByte];
   int16_t output_[kMaxOutputSize];
 };
 
 TEST(NetEqNetworkStatsTest, DecodeFec) {
   MockAudioDecoder decoder(1);
-  NetEqNetworkStatsTest test(kDecoderOpus, &decoder);
+  NetEqNetworkStatsTest test(NetEqDecoder::kDecoderOpus, &decoder);
   test.DecodeFecTest();
   EXPECT_CALL(decoder, Die()).Times(1);
 }
 
 TEST(NetEqNetworkStatsTest, StereoDecodeFec) {
   MockAudioDecoder decoder(2);
-  NetEqNetworkStatsTest test(kDecoderOpus, &decoder);
+  NetEqNetworkStatsTest test(NetEqDecoder::kDecoderOpus, &decoder);
   test.DecodeFecTest();
   EXPECT_CALL(decoder, Die()).Times(1);
 }
 
 TEST(NetEqNetworkStatsTest, NoiseExpansionTest) {
   MockAudioDecoder decoder(1);
-  NetEqNetworkStatsTest test(kDecoderOpus, &decoder);
+  NetEqNetworkStatsTest test(NetEqDecoder::kDecoderOpus, &decoder);
   test.NoiseExpansionTest();
   EXPECT_CALL(decoder, Die()).Times(1);
 }
 
 }  // namespace test
 }  // namespace webrtc