Grid Tool is a grid drawing utility program for analyze and design testing.
Grid Tool — description
Grid Tool is a lightweight utility program for developers which draws a grid on top of the phone screen. Grid Tool support floating menu draw over other apps so you can use it for UI testing, analyze other apps or use as a drawing utility for artists.
Only "Display over other apps" permissions is needed, no additional permission are required.
Grid Tool is free, lightweight (less than 5MB) and customizable.