Now I'm remaking restriction,and I didn't find interface for restriction in windowmanager on master branch,
so from homescreen-service respective,I made a sequence in restriction.png.
In this sequence, I assumed two points:

• windowmanager can provide two event: "RestrictionOn" and "RestrictionOff".
• windowmanager known when would show restriction or hide restriction.

Please checking this design from windowmanager respective.Thank you in advance.

In addition,when windowmanager could commit this function to gerrit or providing a temporary version?