Web apps (web sites) are very powerful tools, however "background location" does not work with them.
Background Location Broadcaster is a tool, which lets the user send the location, to web apps (uris), continuously in the background. Note! Only a few sites can be used with the app: List of controllable sites.
How to install:
The app is not on Google Play, but you can download it to your Android device, then go to "Downloads" or "Files" from where you should be able to install it