It looks like Facebook is bypassing Google Play by sending updates for their Android app straight to your device. While we have still to see the update arrive in our devices Liliputing has reported that the update auto downloads and will give you a notification once it is ready to download.
Another feature that is included in this update is that future updates will be automatically downloaded without the app notifying you. Included in the permissions of the recent update is the line “download files without notification.” This means that future updates will be automatically downloaded without the need for Google Play. You will still get a notification once the update has downloaded completely and is ready to be installed. Those concerned about data charges have nothing to worry about since the app only downloads updates over a Wi-Fi network and not through your network carrier.
We are really not sure as to why Facebook is implementing this new change in the way they are updating their Android app. One possible reason is they might need a faster method to deploy their updates and passing through Google Play might delay the process.
One problem that may arise because of this is that Android devices will have a greater chance of getting malware. Before you can install the updates from Facebook you will need to enable the “Allow installation of apps from unknown sources” feature. If you forget to disable this feature after installing the update then you place your device at risk from malware.