Yesterday I added an experimental package dev-util/chromium-tools, that contains wrappers for depot_tools, a set of scripts required to fetch and work with Chromium sources.
If you are interested in working on Chromium (the open source web browser project), chromium-tools may be useful for you. Right after installing, gclient, gcl, and drover will be available in your PATH, and auto-updating of those tools will be handled transparently.
There is a git repository for the project, and patches are welcome!