frameworks/base/policy/src/com/android/internal/policy/impl/LockPatternKeyguardView.java

This is where the lockscreen that is created
is returned so that the phone can create the lockscreen
when the phone is turned off.
My thinking is to create an intent that must be explictly
set to allow users to set a lockscreen
if the user does not have a lockscreen app installed,
other than the systems, then the sytems will always be used.
The lockcsreen app should only contain the lockscreen for
for when no other security is enabled, as the system does.
If security is enabled then this lockscreen should never
be shown even with the intent.