Support Opus Ambisonics playback

media/base/audio_decoder_config.cc

Index: media/base/audio_decoder_config.cc
diff --git a/media/base/audio_decoder_config.cc b/media/base/audio_decoder_config.cc
index 253c82b147c96b0304ce49d83ec7c4334bb78fdb..53b7be6e62174ebbcb6af31d1c5d27a502c0ffb0 100644
--- a/media/base/audio_decoder_config.cc
+++ b/media/base/audio_decoder_config.cc
@@ -50,8 +50,10 @@ void AudioDecoderConfig::Initialize(AudioCodec codec,
   seek_preroll_ = seek_preroll;
   codec_delay_ = codec_delay;
 
-  int channels = ChannelLayoutToChannelCount(channel_layout_);
-  bytes_per_frame_ = channels * bytes_per_channel_;
+  // If |channel_layout_| is CHANNEL_LAYOUT_DISCRETE, |channels_| and
+  // |bytes_per_frame_| will be overwritten in set_channels_for_discrete()
+  channels_ = ChannelLayoutToChannelCount(channel_layout_);
+  bytes_per_frame_ = channels_ * bytes_per_channel_;
 }
 
 AudioDecoderConfig::~AudioDecoderConfig() {}