This is purely marketing AFAIT. I don't see how it provides any protection against the 5 eyes or having one's google account breached. The encryption/decription is done with javascript code served to your browser by google (= can be hijacked/changed/…)
The only way to do client side encryption is PGP on a native client distributed by a third party.
The only way to do client side encryption is PGP on a native client distributed by a third party.