I moved some of the functions currently implemented in the ebuilds for
www-client/chromium and www-client/google-chrome into a new eclass
"chromium.eclass".

This will allow the two packages to share some code, and it will reduce
the size of each chromium ebuild by around 4K (18K -> 14K).

I have attached a copy of the eclass and its manpage. You may also view
the eclass in my overlay:

https://bitbucket.org/floppym/floppym-overlay/src/default/eclass/chromium.eclass

Here is how it would be used in the www-client/chromium package:

https://bitbucket.org/floppym/floppym-overlay/changeset/fbf6de591da7

Please review.