Support Opus Ambisonics playback

media/renderers/audio_renderer_impl.h

Index: media/renderers/audio_renderer_impl.h
diff --git a/media/renderers/audio_renderer_impl.h b/media/renderers/audio_renderer_impl.h
index 1341183389ace32ddffb81e1e595dd680f19a22f..e4d6e94dfa0758c2e673ecae80538fd21fc0f6a8 100644
--- a/media/renderers/audio_renderer_impl.h
+++ b/media/renderers/audio_renderer_impl.h
@@ -248,6 +248,10 @@ class MEDIA_EXPORT AudioRendererImpl
   // Whether the stream is possibly encrypted.
   bool is_encrypted_;
 
+  // Similar to |last_decoded_channel_layout_|, used to configure the channel
+  // mask given to the |algorithm_| for efficient playback rate changes.
+  int last_decoded_channels_;
+
   // After Initialize() has completed, all variables below must be accessed
   // under |lock_|. ------------------------------------------------------------
   base::Lock lock_;