Move Liveness from DemuxerStreamProvider to DemuxerStream.

media/base/demuxer_stream.cc

Index: media/base/demuxer_stream.cc
diff --git a/media/base/demuxer_stream.cc b/media/base/demuxer_stream.cc
index e55a1638674828b12e9d6738cd52412fb4854add..f56538a11bd2054c450761e83904a9ba6b79e193 100644
--- a/media/base/demuxer_stream.cc
+++ b/media/base/demuxer_stream.cc
@@ -8,6 +8,12 @@ namespace media {
 
 DemuxerStream::~DemuxerStream() {}
 
+// Most DemuxerStream implementations don't specify liveness. Returns unknown
+// liveness by default.
+DemuxerStream::Liveness DemuxerStream::liveness() {
+  return DemuxerStream::LIVENESS_UNKNOWN;
+}
+
 // Most DemuxerStream implementations don't need to convert bit stream.
 // Do nothing by default.
 void DemuxerStream::EnableBitstreamConverter() {}