MSE: Add StreamParser buffer remuxing utility and tests

media/base/stream_parser.h

Index: media/base/stream_parser.h
diff --git a/media/base/stream_parser.h b/media/base/stream_parser.h
index 39dbc34f928b6b321d533065b912472d08616dd0..96f675213d44116df595f6ebf2f22e47d6beacc0 100644
--- a/media/base/stream_parser.h
+++ b/media/base/stream_parser.h
@@ -8,6 +8,7 @@
 #include <deque>
 #include <map>
 #include <string>
+#include <vector>
 
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
@@ -111,6 +112,23 @@ class MEDIA_EXPORT StreamParser {
   DISALLOW_COPY_AND_ASSIGN(StreamParser);
 };
 
+// Appends to |merged_buffers| the provided buffers in decode-timestamp order.
+// Any previous contents of |merged_buffers| is assumed to have lower
+// decode timestamps versus the provided buffers. All provided buffer queues
+// are assumed to already be in decode-timestamp order.
+// Returns false if any of the provided audio/video/text buffers are found
+// to not be in decode timestamp order, or have a decode timestamp less than
+// the last buffer, if any, in |merged_buffers|. Partial results may exist
+// in |merged_buffers| in this case. Returns true on success.
+// No validation of media type within the various buffer queues is done here.
+// TODO(wolenetz/acolwell): Merge incrementally in parsers to eliminate
+// subtle issues with tie-breaking. See http://crbug.com/338484.
+MEDIA_EXPORT bool MergeBufferQueues(
+    const StreamParser::BufferQueue& audio_buffers,
+    const StreamParser::BufferQueue& video_buffers,
+    const StreamParser::TextBufferQueueMap& text_buffers,
+    StreamParser::BufferQueue* merged_buffers);
+
 }  // namespace media
 
 #endif  // MEDIA_BASE_STREAM_PARSER_H_