Consider text tracks in the frame processor for new media segments.

media/filters/legacy_frame_processor.cc

Index: media/filters/legacy_frame_processor.cc
diff --git a/media/filters/legacy_frame_processor.cc b/media/filters/legacy_frame_processor.cc
index de1deb7dfe0b983a6fff269891ef69c1075e5e68..ae3b3e5738ae89689be4affff162e7bcfbaac12f 100644
--- a/media/filters/legacy_frame_processor.cc
+++ b/media/filters/legacy_frame_processor.cc
@@ -90,7 +90,9 @@ bool LegacyFrameProcessor::ProcessFrames(
 
     for (TrackBufferMap::iterator itr = track_buffers_.begin();
          itr != track_buffers_.end(); ++itr) {
-      itr->second->stream()->OnNewMediaSegment(segment_timestamp);
+      // Let text tracks manage their own segment start times.
+      if (itr->second->stream()->type() != DemuxerStream::TEXT)

[wolenetz, 2014/04/02 22:54:45]

|*new_media_segment| can become true between ProcessFrames() calls.
For example, every time the stream parser identifies a new media segment is
beginning, it sets this flag true.

This change now excludes text tracks from recognizing new media segment starts
or when audio or video discontinuities in the current media segment have been
detected. The former may be ok (see http://crbug.com/351489), but perhaps we
should retain some behavior like "if there's any resulting filtered text frames,
and |*new_media_segment| became true prior to Append or during audio/video/text
filtering, then also let text streams know OnNewMediaSegment"? The new
FrameProcessor (WIP@ https://codereview.chromium.org/180153003/) complies more
rigidly with spec especially around discontinuity detection.

[DaleCurtis, 2014/04/02 23:02:27]

That sounds like overly complicated logic which wouldn't even catch most cases.
I defer to you and acolwell@ on what you want to do here. 

[acolwell GONE FROM CHROMIUM, 2014/04/03 00:26:52]

I believe the root of the problem is that the text track buffers are not being
taken into account when computing segment_timestamp. Doing this would require
interleaving the OnTextBuffers() code into this function. Video, audio, and text
should all be using the same segment start timestamp.

[DaleCurtis, 2014/04/08 20:42:30]

Done.

+        itr->second->stream()->OnNewMediaSegment(segment_timestamp);
     }
   }
 
@@ -246,6 +248,18 @@ bool LegacyFrameProcessor::OnTextBuffers(
   if (filtered_buffers.empty())
     return true;
 
+  if (*new_media_segment) {
+    *new_media_segment = false;
+    for (TrackBufferMap::iterator itr = track_buffers_.begin();
+         itr != track_buffers_.end();
+         ++itr) {
+      if (itr->second->stream()->type() == DemuxerStream::TEXT) {
+        itr->second->stream()->OnNewMediaSegment(
+            filtered_buffers.front()->GetDecodeTimestamp());
+      }
+    }
+  }
+
   return AppendAndUpdateDuration(track->stream(), filtered_buffers);
 }