Pocket lands as Firefox's second System Add-on
Mozilla plans to release the built-in Pocket integration of Firefox as a system add-on with Firefox 46.
The organization made the decision to remove the native integration of certain features of the web browser as part of its "Go Faster" initiative to re-release these features as system add-ons.
It hopes that the move will improve development, testing and deployment of these features as they can be updated just like regular add-ons this way which means that Mozilla does not need to publish an update for the whole browser if it wants to update one of the features that it turned into system add-ons.
A basic example where this can be beneficial is the deployment of bug or security updates for these components. Mozilla had to build and distribute a new version of Firefox previously in those cases whereas it can simply push out an update for the component under the new system speeding things up along the way.
The native integration of Pocket in Firefox was controversial in nature even if you consider that Firefox users were able to disable the feature completely in the browser so that it would not use any resources.
At least some users of the browser believed that Mozilla wasted development time on the integration that the organization could have spend elsewhere. Mozilla claimed that it was not benefiting monetarily from the integration of Pocket in Firefox but stated months later that it had a revenue share agreement with Pocket.
It is unclear how many Firefox users are making use of Pocket as statistics have not been released by Mozilla or Pocket. Even if you consider a high usage count of 1% or even 5% of all Firefox users, it would mean that Mozilla integrated a feature in Firefox that 99% or 95% of all users don't use.
Pocket System Add-on
Users of Firefox Nightly, the cutting edge development channel, may have noticed already that Pocket has been released as a system add-on.
While there is no direct indication of that in Firefox's interface (you do find it listed as a browser extension on about:support but that's it), a quick check of the program folder of the browser, and there the browser/features folder reveals that this is indeed the case.
It is the second system add-on that Mozilla released for the browser. The first, Firefox Hello, or Loop, was released as a system add-on back in December 2015.
Side note: The size of the Look system add-on more than doubled in a month's time. It was released with a size of 1211 KB back in December 2015, and has a size of 2987 KB now in early January.
System add-ons are not listed in Firefox's add-manager yet. Mozilla may add them there to provide users with an option to disable them. It is certain however that a remove option won't be made available.