Multistream opus in Chrome.

This change is required to let Chrome encode and decode multistream
Opus audio. It adds WebRTC multistream Opus decoders and encoders as
non-advertised codecs to the audio codec factory.

The WebRTC default audio codec factory has contained the multistream
opus encoder/decoder since April 25 and April 8 respectively. The
multistream encoders have been tested in WebRTC.

Bug: webrtc:8649
Change-Id: Ie350ab2e052edfd7f18dfa4c67bb397dfa541d1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1609782Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Alex Loiko <aleloi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659048}

content/renderer/BUILD.gn

@@ -653,7 +653,9 @@ target(link_target_type, "renderer") {
     "//third_party/webrtc/api/audio_codecs/g722:audio_encoder_g722",
     "//third_party/webrtc/api/audio_codecs/isac:audio_decoder_isac",
     "//third_party/webrtc/api/audio_codecs/isac:audio_encoder_isac",
+    "//third_party/webrtc/api/audio_codecs/opus:audio_decoder_multiopus",
     "//third_party/webrtc/api/audio_codecs/opus:audio_decoder_opus",
+    "//third_party/webrtc/api/audio_codecs/opus:audio_encoder_multiopus",
     "//third_party/webrtc/api/audio_codecs/opus:audio_encoder_opus",
     "//third_party/webrtc/api/video:video_bitrate_allocation",
     "//third_party/webrtc/api/video:video_frame",

content/renderer/media/webrtc/audio_codec_factory.cc

@@ -17,7 +17,9 @@
 #include "third_party/webrtc/api/audio_codecs/g722/audio_encoder_g722.h"
 #include "third_party/webrtc/api/audio_codecs/isac/audio_decoder_isac.h"
 #include "third_party/webrtc/api/audio_codecs/isac/audio_encoder_isac.h"
+#include "third_party/webrtc/api/audio_codecs/opus/audio_decoder_multi_channel_opus.h"
 #include "third_party/webrtc/api/audio_codecs/opus/audio_decoder_opus.h"
+#include "third_party/webrtc/api/audio_codecs/opus/audio_encoder_multi_channel_opus.h"
 #include "third_party/webrtc/api/audio_codecs/opus/audio_encoder_opus.h"
 
 namespace content {
@@ -73,7 +75,8 @@ CreateWebrtcAudioEncoderFactory() {
   return webrtc::CreateAudioEncoderFactory<
       webrtc::AudioEncoderOpus, webrtc::AudioEncoderIsac,
       webrtc::AudioEncoderG722, webrtc::AudioEncoderG711,
-      NotAdvertisedEncoder<webrtc::AudioEncoderL16>>();
+      NotAdvertisedEncoder<webrtc::AudioEncoderL16>,
+      NotAdvertisedEncoder<webrtc::AudioEncoderMultiChannelOpus>>();
 }
 
 rtc::scoped_refptr<webrtc::AudioDecoderFactory>
@@ -81,7 +84,8 @@ CreateWebrtcAudioDecoderFactory() {
   return webrtc::CreateAudioDecoderFactory<
       webrtc::AudioDecoderOpus, webrtc::AudioDecoderIsac,
       webrtc::AudioDecoderG722, webrtc::AudioDecoderG711,
-      NotAdvertisedDecoder<webrtc::AudioDecoderL16>>();
+      NotAdvertisedDecoder<webrtc::AudioDecoderL16>,
+      NotAdvertisedDecoder<webrtc::AudioDecoderMultiChannelOpus>>();
 }
 
 }  // namespace content