I'm unsure what caused this to start occurring, but I don't believe it's
webrtc's fault, so I'm adding a suppression for now.
BUG=webrtc:7973
TBR=kjellander@webrtc.org
NOTRY=true
Review-Url: https://codereview.webrtc.org/2977723003
Cr-Commit-Position: refs/heads/master@{#18981}