rohks 87d91ed19e Add timestamp to Metadata
`MetadataRenderer` is updated to output `Metadata` with its presentation time, in microseconds.

PiperOrigin-RevId: 457444718
(cherry picked from commit b2831d8559713b757feb3f15a2c828db0e5ecd7c)
2022-06-27 11:31:10 +00:00
..
2022-06-27 11:31:10 +00:00