I have an older Chromebook that could not be updated due to its age. I also have an older Acer Aspire running Win 10. This has become extremely slow. The 'system interrupts ' take over the cpu. I purchased an ACER Chromebook at Bestbys for $99 yesterday. After doing the initial setup I was able to log on to my yahoo email without entering my password. Just for a test, Linkedin, pcqanda, Facebook, and others did not require the entry of a password. The question is how did all these passwords get transferred?
My guess is that because Chromebook uses the cloud and you probably used the same credentials. e.g. username or whatever, then the passwords were retrieved from the cloud.