I'm sorry - but this just comes across as wild paranoia - you're basically saying they could read your data - so they must?
That's like saying your school could install cameras in the toilets - so they must have?
Or that your landlord is secretly going through your stuff, because he has keys?
Actually - the Chromium browser project is open source:
It's what Google Chrome is built on - you could just compile that if you wanted. (You lose out on a bunch of integrations - but it sounds like that might be what you want, anyhow).