tabs.getSelected has been deprecated since Chrome 33. Instead,
use tabs.query.

Fixes #35663

Change-Id: I4f7f17f948987aff8409ac8210f04eb1f7ebf908
Reviewed-on: https://go-review.googlesource.com/c/go/+/207402Reviewed-by: Andrew Bonventre <andybons@golang.org>