These helper functions will be useful when making the legacy video
codecs injectable.
Bug: webrtc:7925
Change-Id: Id5a480666f07eccc3116d2c2e61803cc4daf7c9f
Reviewed-on: https://webrtc-review.googlesource.com/88365
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23954}