Password Checkup Chrome extension is designed to keep an eye on current data breaches and announce its users if their accounts have been impacted by recent security breaches. It will automatically warn the user and suggest a password change whenever it detects that the username and password combination used on the current site is one of over 4 billion credentials Google knows to have been previously compromised. Google already resets passwords of user accounts who might have been affected by third-party breaches as part of an effort to limit the potential security impact on its users’ accounts.
Source: https://www.bleepingcomputer.com/news/google/google-launches-password-checkup-extension-to-alert-users-of-data-breaches/