I have been on a goose chase trying to track this down. I think I may have figured how to do for data going forward. But need to certainly reprocess all of my old data.
Process testing now for data going forward...
There is a field in processing rules configuration "Customer Perspective" that I setup to dump into a eVar. From there I am hoping the "Background/Foreground" value will populate in the data feed. Hopefully this will also unlock data warehouse segmentation as well. Will update thread here if on if this works.
Customer Perspective URL Parameter
The Adobe Analytics data collection process allows you to set a query string parameter specifying the customer perspective (denoted as the "cp" query string parameter). This field specifies the state of the end user's digital application. This helps you know whether a hit was generated while a mobile app was in a background state.