Enable Built-in Facebook Messenger in Mozilla Firefox

If you are a Mozilla Firefox user and also love spending your time on Facebook, here is an excellent news for you.
Currently the feature is new and only Facebook integration has been implemented in the latest Firefox version but in future more social networks will be added.
If you are not a social network fan, don't worry. This feature it not enabled by default. It gets automatically enabled if you access these social networking websites frequently.

If you don't want to wait and want to turn the feature on immediately, you can do it using following simple steps:

Step 1. First go to following official Facebook URL to turn Facebook Messenger on in Firefox:

Turn Facebook Messenger On in Firefox

Just click on "Turn On" button in the above link and it'll immediately enable the Facebook API in Firefox.

Step 2. As soon as you turn the Facebook messenger on, it'll add Facebook buttons in Firefox toolbar and Facebook chat sidebar in right-side of Firefox window as shown in following screenshot:

The Facebook buttons in Firefox toolbar will help you in checking your notifications, messages, etc without going to actual Facebook website.
Facebook chat sidebar will allow you chat with your friends just like you do in original Facebook website.
You can disable the Facebook chat sidebar by clicking on Facebook button present in Firefox toolbar and unchecking "Show sidebar" option.

If you don't like the Facebook messenger and want to disable it, you can click on "Remove from Firefox" option using Facebook button in toolbar.
Alternate way to enable Facebook Messenger: You can also use a built-in tweak to enable and activate the whole social API in Firefox. Just follow these simple steps:

Step 1. Open Firefox and type about:config in the addressbar and press Enter. It'll confirm, click on I'll be careful, I promise! button.

Step 2. Now type social in the Filter box and look for following boolean keys:

    social.active
    social.enabled

Step 3. Both keys would be set to false. Double-click or right-click on the keys and select "Toggle". It'll set their values to true.