IMO just because it's open source doesn't mean it's safe.
I would trust a closed source project that has been thoroughly and extensively vetted by a third-party auditor I trust far more than an open source project that has no audit for me to reference.
As I am not a professional security auditor, my ability to understand the minutiae of developer decisions (intentional and unintentional) in some multi-million-LOC project is basically a limit approaching zero. My looking at the source code to give myself a false sense of security would only increase my risk, IMO.
It's like a restaurant tells you "yeah we have a clean kitchen, you can go take a quick look yourself!" and it's like, do you know to check that water and disinfectant buckets can't be within x feet of each other? To temp every fridge and warmer to ensure no danger zones? To monitor glove usage and hair net usage? And a thousand other things?
Being open source basically means that a nice auditor could do some audit work for free to help the community, but that's about it from my perspective.
Unless some of you are actively code reviewing the entirety of Chromium prior to launching any build of it ???