You are confusing security and privacy. And with regards to privacy, it depends on the type of account you are signed into, business pay account, school, personal "free" account, it depends on the app, in exactly the same way a Firefox browser would send day back to Mozilla on Linux, or IE would on Windows..
Chrome OS is very secure, as it unlike any other OS, it's runtime is a complete chain of trust, each component during load checking the next. There is no way anything can slip between those cracks, and it's security is proven in real real world. You simply don't get Chrome OS malware, you might get rouge add-ons within their own sandbox, but the host OS can't be modified.
The other side effect of all this, is s Chromebook will not slow down over time like windows, Mac and Linux PC's. The OS never bloats, as it never changes. My 3yr old Chromebook bis as fast today as it was the day I bought it, and still delivers 12hr use from a charge, which is unheard of with traditional laptops.
Biting the hand that feeds IT
