Have Google Analytics code still run on force download
For that kind of thing, you can use the GA "event tracking" to track the click event for the file download. 


  Events are user interactions with content that can be tracked independently from a web page or a screen load. Downloads, mobile ad clicks, gadgets, Flash elements, AJAX embedded elements, and video plays are all examples of actions you might want to track as Events.


The GA module provides some click event tracking for files by default in the config, else you can check here for more info on adding such a feature:

https://developers.google.com/analytics/devguides/collection/analyticsjs/events