lxsession-default-apps software package provides utility to configure lxsession and its default applications, 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 lxsession-default-apps
lxsession-default-apps is installed in your system.
Make ensure the lxsession-default-apps package were installed using the commands given below,
$ sudo dpkg-query -l | grep lxsession-default-apps *
You will get with lxsession-default-apps package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | X Window System software |
| Package | lxsession-default-apps |
| Version | 0.4.9.2+git20140410-0ubuntu1 |
| Description | utility to configure lxsession and its default applications |
| Sub Section | x11 |