Chronium has been removed and replace with a new package.

[kasperhartwich]

When trying to install chronium on newer raspbian images, you'll get this error:
$ sudo apt-get install chromium
sudo: unable to resolve host raspberrypi
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package chromium is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or is only available from another source
However the following packages replace it:
chromium-inspector chromium-bsu

E: Package 'chromium' has no installation candidate

They added chronium as a new package to the raspberry pi repo, so use this instead:
sudo apt-get install chromium-browser