There's no Chrome Beta for iOS, so you can't enable the data compression proxy. This feature is gradually rolled out and some lucky Chrome users were invited to try it: "You're invited. Join a limited preview of a new feature from Chrome. Save bandwidth and browse more securely."
Here's a video that shows this feature:
If you use Android, you can install Chrome Beta and enable this feature in the settings or use the regular Chrome version and wait until you get an invite.
{ Gracias, Adrià Vilanova MartÃnez. }
