peerConnectionParameters.videoCodec can be null in some cases. Previously, this would cause a crash in AppRTCMobile. Bug: b/67938523 Change-Id: I30ebf0f91fad23a3cf34946736b9f4e6c266277f Reviewed-on: https://webrtc-review.googlesource.com/14200 Reviewed-by: Magnus Jedvert <magjed@webrtc.org> Commit-Queue: Sami Kalliomäki <sakal@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20372}