We're going to stop extracting files from the android apk to the application directory at all, so we don't need to keep track of which files should be removed when upgrading. Instead, we should remove all files (except those that are extracted by android at install time, i.e. libmozutils.so and libplugin-container.so (that one comes from bug 686466). Even better, we should remove the files at a later time than startup.
It looks like the code reading removed-files was removed.