Add status parameter to DemuxerStream::ReadCB

media/base/demuxer_stream.h

Index: media/base/demuxer_stream.h
diff --git a/media/base/demuxer_stream.h b/media/base/demuxer_stream.h
index 1266a712687c3b8030db72ea28acb8c4dc1c3030..d4f008ccdef231b8e09d03394e3cf20818fc36d8 100644
--- a/media/base/demuxer_stream.h
+++ b/media/base/demuxer_stream.h
@@ -26,12 +26,27 @@ class MEDIA_EXPORT DemuxerStream
     NUM_TYPES,  // Always keep this entry as the last one!
   };
 
+  enum Status {

[Ami GONE FROM CHROMIUM, 2012/06/26 00:33:21]

Before this CL, ReadCB had 3 possible return scenarios (normal, EOS, abort). 
After this CL, it has 4 possible return scenarios (above + config change).  Does
it not make sense to promote EOS to a Status now that you must pass/inspect
Status anyway?

[acolwell GONE FROM CHROMIUM, 2012/07/12 01:19:38]

I believe it does make sense. Mind if I defer this to a follow-on CL?

+    kOk,
+    kAborted,
+    kConfigChanged,
+  };
+
   // Request a buffer to returned via the provided callback.
   //
-  // Non-NULL buffer pointers will contain media data or signal the end of the
-  // stream. A NULL pointer indicates an aborted Read(). This can happen if the
-  // DemuxerStream gets flushed and doesn't have any more data to return.
-  typedef base::Callback<void(const scoped_refptr<DecoderBuffer>&)> ReadCB;
+  // The first parameter indicates the status of the read.
+  //  kOk : Indicates the second parameter is Non-NULL and contains media data

[Ami GONE FROM CHROMIUM, 2012/06/26 00:33:21]

These comments belong at the enum declaration, not here.

[acolwell GONE FROM CHROMIUM, 2012/07/12 01:19:38]

Done.

+  //        or the end of the stream.
+  //  kAborted : Indicates an aborted Read(). This can happen if the
+  //             DemuxerStream gets flushed and doesn't have any more data to
+  //             return. The second parameter MUST be NULL when this status is
+  //             return.

[Ami GONE FROM CHROMIUM, 2012/06/26 00:33:21]

s/\./ed./

[acolwell GONE FROM CHROMIUM, 2012/07/12 01:19:38]

Done.

+  //  kConfigChange : Indicates that the decoder configuration has changed and a
+  //                  call to audio_decoder_config() or video_decoder_config()

[Ami GONE FROM CHROMIUM, 2012/06/26 00:33:21]

This phrasing implies that calling [av]_d_c() on a demuxer stream will
reconfigure a decoder or something.  Rephrase?

[acolwell GONE FROM CHROMIUM, 2012/07/12 01:19:38]

Done.

+  //                  is needed before more data is returned. The second
+  //                  parameter MUST be NULL when this status is return.

[Ami GONE FROM CHROMIUM, 2012/06/26 00:33:21]

ditto

[acolwell GONE FROM CHROMIUM, 2012/07/12 01:19:38]

Done.

+  typedef base::Callback<void(Status, const scoped_refptr<DecoderBuffer>&)>
+      ReadCB;
   virtual void Read(const ReadCB& read_cb) = 0;
 
   // Returns the audio decoder configuration. It is an error to call this method