Fix seeking when the start time is non-zero.

media/filters/chunk_demuxer.cc

Index: media/filters/chunk_demuxer.cc
diff --git a/media/filters/chunk_demuxer.cc b/media/filters/chunk_demuxer.cc
index c4afc02c5430fccdb6d1f791c9789fb7fa80f44e..d33c7864ce11f8d49584eb9b1117ceb809410ae8 100644
--- a/media/filters/chunk_demuxer.cc
+++ b/media/filters/chunk_demuxer.cc
@@ -1102,10 +1102,6 @@ DemuxerStream* ChunkDemuxer::GetStream(DemuxerStream::Type type) {
   return NULL;
 }
 
-TimeDelta ChunkDemuxer::GetStartTime() const {
-  return TimeDelta();
-}
-
 base::Time ChunkDemuxer::GetTimelineOffset() const {
   return timeline_offset_;
 }
@@ -1607,7 +1603,7 @@ void ChunkDemuxer::OnSourceInitDone(
     return;
   }
 
-  SeekAllSources(GetStartTime());
+  SeekAllSources(base::TimeDelta());
   StartReturningData();
 
   if (duration_ == kNoTimestamp())