This is good for a few reasons:
- We avoid grabing a lock twice.
- We avoid an unnecessary copy.
- We avoid a race where a packet could potentially be removed before the
second time we call GetCodecHeader.
BUG=None
Review-Url: https://codereview.webrtc.org/3009833002
Cr-Commit-Position: refs/heads/master@{#19635}