Support Opus Ambisonics playback

media/formats/webm/webm_audio_client.cc

Index: media/formats/webm/webm_audio_client.cc
diff --git a/media/formats/webm/webm_audio_client.cc b/media/formats/webm/webm_audio_client.cc
index d6eda2f3af6d29c6ba163a06a451847ff2a437c6..0cf3492346d8461dca040220fb45aa3484dc2eab 100644
--- a/media/formats/webm/webm_audio_client.cc
+++ b/media/formats/webm/webm_audio_client.cc
@@ -50,7 +50,14 @@ bool WebMAudioClient::InitializeConfig(
   if (channels_ == -1)
     channels_ = 1;
 
-  ChannelLayout channel_layout =  GuessChannelLayout(channels_);
+  bool is_opus_discrete = false;
+  if (audio_codec == kCodecOpus && codec_private.size() >= 19) {
+    int mapping_family = codec_private[18];
+    is_opus_discrete = mapping_family == 2;
+  }
+  ChannelLayout channel_layout = is_opus_discrete && channels_ > 8
+                                     ? CHANNEL_LAYOUT_DISCRETE
+                                     : GuessChannelLayout(channels_);
 
   if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED) {
     MEDIA_LOG(ERROR, media_log_) << "Unsupported channel count " << channels_;
@@ -82,6 +89,7 @@ bool WebMAudioClient::InitializeConfig(
                      base::TimeDelta::FromMicroseconds(
                          (seek_preroll != -1 ? seek_preroll : 0) / 1000),
                      codec_delay_in_frames);
+  config->SetChannelsForDiscrete(channels_);
   return config->IsValidConfig();
 }