DevicePolicyManager is a Java class in Android where device policies (password quality etc) can be set by a third party Device Administrator application.
Methods and constants in DevicePolicyManager are shown here:
http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html
A tutorial to write a Device Administrator application can be found here:
http://developer.android.com/guide/topics/admin/device-admin.html