Ok, I think I understand what you're saying. I decided to test the theory.
Currently, I am signed in to google and I'm using Chrome. So, I signed into the Chrome browser as well, but used another account. I gave Chrome the OK to sync everything, then after a few minutes I signed out of Chrome. My original account remained signed in to the google services.
I went to activity.google.com to see what content was in my history there. Only the sites I had visited with my primary account was there.
Then, I checked Chrome's browser history to see if the content from the account I had just disconnected remained, but it didn't.
I also checked my Chrome saved passwords after reverting my changes. Everything appears normal there, too.
If I've replicated your scenario correctly, I think you're pretty safe if you disconnected your account from Chrome. How much do you trust this friend? If you feel uncomfortable, you can change your passwords on your account as well. But I'd say you're probably in the clear.
This is a good example of why I don't sign into the chrome browser. I also know a tale of a friend's boss who used this feature, and one day when he got to the office, he opened up Chrome and lo and behold, all of the porn tabs from his home computer magically appeared right there for all his employees to see.