Push Notifications: Chrome v49 doesn't display notifications

[hoverduck]

Steps to reproduce

1. Running Chrome v49 for either Linux/OSX/Windows (obtained here)
2. Enable desktop notifications at https://wordpress.com/me/notifications
3. Spawn a new notification

What I expected

To receive a desktop popup

What happened instead

Nothing but the badge on the notification icon

Browser / OS version

Linux / OSX / Windows Chrome v49

Context / Source

manual-testing

[mjuhasz]

Chrome versions 40-49 support web push notifications, but with a reduced feature set (in particular, these versions do not support encryption).

Our feature detection shows the browser as supporting web push but because of the missing encryption functionality, sending notifications fails.

Chrome 49 is not supported by the vendor anymore, and it is not covered by the Calypso support policy either: at the moment, the latest two versions of Chrome are v51 and v50, they both work with our implementation.

Nevertheless we are planning to improve the experience for those on obsolete Chrome versions.