How does Android handle applications like MP3 player apps that run when the screen is locked (i.e. the user has to input their pin)?
Obviously Android doesn't just let applications like music players run as root, as I have faith that the Android community understands the principle of least privilege. So how is this behavior implemented?
EDIT:
I apologize as my original question was too broad. Perhaps the better question here is "With what permissions does the Android lock screen operate?"