Convert CNG into C++ and remove it from AudioDecoder

webrtc/modules/audio_coding/neteq/decoder_database_unittest.cc

 /*
  *  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 215 matching lines @@
   EXPECT_TRUE(changed);
   decoder = db.GetActiveDecoder();
   ASSERT_FALSE(decoder == NULL);  // Should get a decoder here.
 
   // Remove the active decoder, and verify that the active becomes NULL.
   EXPECT_EQ(DecoderDatabase::kOK, db.Remove(103));
   EXPECT_EQ(NULL, db.GetActiveDecoder());
 
   // Set active CNG codec.
   EXPECT_EQ(DecoderDatabase::kOK, db.SetActiveCngDecoder(13));
-  decoder = db.GetActiveCngDecoder();
-  ASSERT_FALSE(decoder == NULL);  // Should get a decoder here.
+  ComfortNoiseDecoder* cng = db.GetActiveCngDecoder();
+  ASSERT_FALSE(cng == NULL);  // Should get a decoder here.
 
   // Remove the active CNG decoder, and verify that the active becomes NULL.
   EXPECT_EQ(DecoderDatabase::kOK, db.Remove(13));
   EXPECT_EQ(NULL, db.GetActiveCngDecoder());
 
   // Try to set non-existing codecs as active.
   EXPECT_EQ(DecoderDatabase::kDecoderNotFound,
             db.SetActiveDecoder(17, &changed));
   EXPECT_EQ(DecoderDatabase::kDecoderNotFound,
             db.SetActiveCngDecoder(17));
 }
 }  // namespace webrtc