def METHOD_NAME(self, obj):
    for path, files in obj.files.walk():
        for f in files:
            dest = mozpath.join(obj.install_target, path, f.target_basename)
            obj_path = mozpath.join(self.environment.topobjdir, dest)
            if obj_path.endswith(".in"):
                obj_path = obj_path[:-3]
            if isinstance(obj, FinalTargetPreprocessedFiles):
                assert os.path.exists(obj_path), "%s should exist" % obj_path
                pp_info = generate_pp_info(obj_path, obj.topsrcdir)
            else:
                pp_info = None
            base = (
                obj.topobjdir
                if f.full_path.startswith(obj.topobjdir)
                else obj.topsrcdir
            )
            self._install_mapping[dest] = (
                mozpath.relpath(f.full_path, base),
                pp_info,
            )