[GENERAL] Google Cloud Platform, snapshots and WAL

Hi everyone,

     I have my PostgreSQL 9.5 server running on a VM instance on Google
Compute Engine (Google Cloud Platform) on Debian Jessie (8.3), and I
have another dedicated VM instance that, every night at 3.00, takes a
snapshot of the whole disk, without stopping the PG instance itself.
Snapshots are stored and kept by Google in an incremental way, and we
keep the last 2 weeks of history.
The question is: Keeping all two weeks worth of pg_xlog files, I don't
think I still need a periodic pg_basebackup to perform PITR, do I?

Thanks in advance,
Moreno.