gnome-shell-extension-autohide software package provides gnome shell automatic topbar hider, you can install in your Ubuntu 14.04 LTS (Trusty Tahr) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gnome-shell-extension-autohide
gnome-shell-extension-autohide is installed in your system.
Make ensure the gnome-shell-extension-autohide package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnome-shell-extension-autohide*
You will get with gnome-shell-extension-autohide package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | GNOME |
| Package | gnome-shell-extension-autohide |
| Version | 20140113-1 |
| Description | gnome shell automatic topbar hider |
| Sub Section | GNOME |