Do you want all of another Google Account's Web Passwords? Do you want to log into their bank and make transfers? How about logining in to post crazy messages so they get arrested?
Just trick them into login in to Google Chrome. Then when they are not around, change the Windows User Password to whatever you want using numerous methods - easiest is just another Administrator Account or a Domain Controller Interface. Then login as that user. Now open @Chrome. Go to Settings, Advanced, Manage Passwords.
Now click on Export Passwords under the Context Menu left of "Saved Passwords" then click on "Export All Passwords"
For some reason the Security Experts at Google decided to restrict the export process with the WINDOWS ACCOUNT PASSWORD.
You now have all a user's passwords.