Chrome OS is designed to run only off-topic applications (web apps), on an off-topic platform (my understanding is that the platform is minimalist hardware in the same class as an Android tablet). The tag wiki summary doesn't mention anything about Chrome OS, itself, being off-topic.

• Are questions about Chrome OS off-topic?
• If so, should we update the tag wiki to add that fact?
• If not, what would be an example of a question that would be on-topic if the platform, the applications, and programming/development are off-topic?