open a tab to chrome://settings/passwords
Click on a saved password and click "show"
Write down their site / password info. They'll never know you have their login data, no access logs or warnings.
Note that the people freaking out the most about this are incredibly uncreative, because they think this is the only way an unattended computer can be powned, usually combined with weird beliefs about "Security" being a boolean value. Obviously, if you have physical access, you stick a keylogger on there, steal the whole DB of passwords at the binary file level, take over the whole operating system, etc. Also for extra comedy the people most likely to be outraged stereotypically have the same password for all saved sites (LOL) so you really only need to write down one password for that user, and also stereotypically its a variation of "1Password" or their kids name, etc.