Change who allocated the MediaPipe's shared buffer.

mojo/services/media/audio/interfaces/audio_track.mojom

Index: mojo/services/media/audio/interfaces/audio_track.mojom
diff --git a/mojo/services/media/audio/interfaces/audio_track.mojom b/mojo/services/media/audio/interfaces/audio_track.mojom
index 345648557c16198bb655890f610418fc4be44337..a8b8e075fabe904675f44a5e8db5c41b73871cca 100644
--- a/mojo/services/media/audio/interfaces/audio_track.mojom
+++ b/mojo/services/media/audio/interfaces/audio_track.mojom
@@ -19,9 +19,6 @@ struct AudioTrackConfiguration {
   // The media type to use.
   MediaType media_type;
 
-  // Desired maximum buffer size, in frames of audio.
-  uint64 max_frames;
-
   // Ratio of audio frames to media time ticks.
   //
   // Presentation time stamps on audio packets are expressed in units of media