WebRtcVoiceEngine: Use AudioDecoderFactory to generate recv codecs.

webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.cc

Index: webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.cc
diff --git a/webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.cc b/webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.cc
index 48b2f5d437312de30531837bda4c34fb9ca04732..5f4cb157a88fe2abc237412d475b3df6239022ed 100644
--- a/webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.cc
+++ b/webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.cc
@@ -130,7 +130,21 @@ NamedDecoderConstructor decoder_constructors[] = {
 class BuiltinAudioDecoderFactory : public AudioDecoderFactory {
  public:
   std::vector<SdpAudioFormat> GetSupportedFormats() override {
-    FATAL() << "Not implemented yet!";
+    static std::vector<SdpAudioFormat> formats = {

[ossu, 2016/06/16 16:21:25]

kwiberg: If you've got this in one of your CLs, maybe this one should be landed
after that one.

+      { "opus", 48000, 2, {
+          {"minptime", "10" },
+          {"useinbandfec", "1" }
+        }
+      },
+      { "isac", 16000, 1 },
+      { "isac", 32000, 1 },
+      { "G722", 8000,  1 },
+      { "iLBC", 8000,  1 },
+      { "PCMU", 8000,  1 },
+      { "PCMA", 8000,  1 }
+    };
+
+    return formats;
   }
 
   std::unique_ptr<AudioDecoder> MakeAudioDecoder(