UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.110 Safari/537.36

Steps to reproduce the problem:
1. Release a PWA which has lots of exciting features.
2. Advise users they can run it like a native app by choosing menu -> More tools -> Add to desktop.
3. Later realise that this option is mysteriously missing on Mac.

What is the expected behavior?
This option is useful for PWAs and ought to be available on all platforms.

What went wrong?
It's missing on Mac, so our instructions confused Mac users.

Did this work before? N/A 

Chrome version: 57.0.2987.110  Channel: stable
OS Version: 10.12.4
Flash Version: