Stap-A packets should be ignored if NAL unit size is less than one, since that won't even fit the mandatory type header byte. BUG=chromium:617097 R=pbos@webrtc.org, stefan@webrtc.org Review URL: https://codereview.webrtc.org/2039353002 . Cr-Commit-Position: refs/heads/master@{#13057}