While working on MDL-25432, I realized while building activity plan (build_activity_plan()), we call get_backup_activity_task which is checking for course module and creates backup_activity_task.
Also, any backup activity task extends backup_activity_task, in which constructor also checks for course module.

In get_coursemodule_from_id(), we are making two sql calls. It will be nice to pass coursemodule information in constructor of backup_*_activity_task and we can avoid second redundant check.