When comparing Chromium OS vs SliTaz, the Slant community recommends SliTaz for most people. In the question“What are the best Linux distributions for desktops?” SliTaz is ranked 15th while Chromium OS is ranked 56th.
Ranked in these QuestionsQuestion Ranking
Pro Minimalistic interface
Chromium's system UI uses as little screen space as possible by combining apps and standard web pages into a minimal tab strip: While existing operating systems have web tabs and native applications in two separate strips, Chromium OS combines these, giving access to everything from one strip. The tab is the equivalent of a desktop application's title bar; the frame containing the tabs is a simple mechanism for managing sets of those applications and pages.
Because Chromium OS is designed for users who spend most of their computer time on the Web, it is intended for use in computers with little local storage and fast boot-up times.
Pro Safe and requires little to no maintenant
Since you only have the browser, you cannot install applications (outside Chrome Apps which are decently protected by their limited API and the Chrome Web Store). This means no harmful virus, and also nearly no way you can screw your system. Everything will just work.
Pro Very fast
Pro Can add desktop effects
SliTaz has a feature called "Desktop Effects" which can add shadow or fade effects to windows.
Pro Very customizable
SliTaz is very customizable. You can programatically edit and change anything you want on how the OS looks or behaves.
Pro One of the smallest distributions with desktop GUI
The core liveCD is only 35 megabytes. The boot-from-internet option fits on a floppy.
Possibly harms your privacy.
Con No auto-upgrade (unlike Chrome OS)
Chrome OS auto-upgrade the system, but Chromium OS does not. It's possible that they're thinking about adding that feature from the design doc.
Con Install instructions are in French
When first booting SliTaz from a USB or from a Live CD, the installation instructions are in French.
Con Not much variety as to available applications
SliTaz does not have as many applications in its repositories as the bigger distros such as Ubuntu.