Strong reference must be validated when created from weak reference, otherwise crashes are possible and actually observed via Crashlytics. Bug: None Change-Id: I68355080ba3b20119c913a9c7e27edc07b5447cd Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/375901 Commit-Queue: Yury Yarashevich <yura.yaroshevich@gmail.com> Reviewed-by: Kári Helgason <kthelgason@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43837}