I think Youtube is still using Akamai but not as much anymore and Google's CDN is in beta last I checked. Google partners with other major CDN's also.
Cloud CDN itself (https://cloud.google.com/cdn) has been GA for a while, but support for reaching GCS directly from our Load Balancer (https://cloud.google.com/compute/docs/load-balancing/http/us...) and therefore CDN support is in Beta.
Disclosure: I work on Google Cloud.