Enable round-tripping and updating of WebSourceBufferImpl timestamp offset

media/filters/chunk_demuxer_unittest.cc

Index: media/filters/chunk_demuxer_unittest.cc
diff --git a/media/filters/chunk_demuxer_unittest.cc b/media/filters/chunk_demuxer_unittest.cc
index d2c410da9c02c7040b36b8490254b88b8b8cd447..8a840931f7c8af8e7da97c6b547006ec9f838006 100644
--- a/media/filters/chunk_demuxer_unittest.cc
+++ b/media/filters/chunk_demuxer_unittest.cc
@@ -491,6 +491,8 @@ class ChunkDemuxerTest : public testing::Test {
     if (AddId(kSourceId, stream_flags) != ChunkDemuxer::kOk)
       return false;
 
+    EXPECT_EQ(kNoTimestamp(), demuxer_->GetUpdatedTimestampOffset(kSourceId));
+
     AppendInitSegmentWithEncryptedInfo(
         kSourceId, stream_flags,
         is_audio_encrypted, is_video_encrypted);