Switch from a DataPipe per DecoderBuffer to a single one.

media/mojo/interfaces/media_types.mojom

Index: media/mojo/interfaces/media_types.mojom
diff --git a/media/mojo/interfaces/media_types.mojom b/media/mojo/interfaces/media_types.mojom
index 7ce78f64840ad3a2dddad1cc71e1b1586e555afa..9a729b07a897fd2a2db2e6bb98b3e2dbd1551f2f 100644
--- a/media/mojo/interfaces/media_types.mojom
+++ b/media/mojo/interfaces/media_types.mojom
@@ -210,10 +210,4 @@ struct MediaDecoderBuffer {
 
   // Indicates this buffer is part of a splice around |splice_timestamp_usec|.
   int64 splice_timestamp_usec;
-
-  // The payload. Invalid handle indicates an end-of-stream (EOS) buffer.
-  // TODO(tim): This currently results in allocating a new, largeish DataPipe
-  // for each buffer. Remove this once framed data pipes exist, but using this
-  // for now for prototyping audio.
-  handle<data_pipe_consumer>? data;
 };