Support Opus Ambisonics playback

media/base/audio_decoder_config.h

Index: media/base/audio_decoder_config.h
diff --git a/media/base/audio_decoder_config.h b/media/base/audio_decoder_config.h
index 675eb87232ceb5cd722550e7fe02fb50b30ca068..17499048b594b5df9f8070c22613b95dd6defe0e 100644
--- a/media/base/audio_decoder_config.h
+++ b/media/base/audio_decoder_config.h
@@ -63,10 +63,18 @@ class MEDIA_EXPORT AudioDecoderConfig {
   // output only.
   std::string AsHumanReadableString() const;
 
+  void SetChannelsForDiscrete(int channels) {
+    DCHECK(channel_layout_ == CHANNEL_LAYOUT_DISCRETE ||
+           channels == ChannelLayoutToChannelCount(channel_layout_));
+    channels_ = channels;
+    bytes_per_frame_ = channels_ * bytes_per_channel_;
+  }
+
   AudioCodec codec() const { return codec_; }
   int bits_per_channel() const { return bytes_per_channel_ * 8; }
   int bytes_per_channel() const { return bytes_per_channel_; }
   ChannelLayout channel_layout() const { return channel_layout_; }
+  int channels() const { return channels_; }
   int samples_per_second() const { return samples_per_second_; }
   SampleFormat sample_format() const { return sample_format_; }
   int bytes_per_frame() const { return bytes_per_frame_; }
@@ -98,6 +106,7 @@ class MEDIA_EXPORT AudioDecoderConfig {
   SampleFormat sample_format_;
   int bytes_per_channel_;
   ChannelLayout channel_layout_;
+  int channels_;
   int samples_per_second_;
   int bytes_per_frame_;
   std::vector<uint8_t> extra_data_;