grub2-themes-ubuntu-mate software package provides GRand Unified Bootloader, version 2 (ubuntu-mate theme), you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install grub2-themes-ubuntu-mate
grub2-themes-ubuntu-mate is installed in your system.
Make ensure the grub2-themes-ubuntu-mate package were installed using the commands given below,
$ sudo dpkg-query -l | grep grub2-themes-ubuntu-mate *
You will get with grub2-themes-ubuntu-mate package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Administration Utilities |
| Package | grub2-themes-ubuntu-mate |
| Version | 0.3.7 |
| Description | GRand Unified Bootloader, version 2 (ubuntu-mate theme) |
| Sub Section | admin |