frontend: set service to play
frontend: set service to play

Fixes golang/go#21645

Change-Id: I07ca2e63cbaffb96ace0dccf7ee1c112ca5a5417
Reviewed-on: https://go-review.googlesource.com/85036
Reviewed-by: Andrew Bonventre <682ad9f487f614f19e8b7cc5d340bdc8e1c1b128@golang.org>

golang/playground,golang/playground,golang/playground