We hit this CHECK even though the format wasn't even L16, because we
did the checked_cast before testing the codec name.
BUG=chromium:760994
TBR=ossu@webrtc.org
Change-Id: I382a2f841e51944495500f87650258024030d355
Reviewed-on: https://webrtc-review.googlesource.com/1224
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19835}