We know that Google protects our account and help customers in detecting and preventing security issues. They already built automatically resetting the password for Google products if it gets breached by any one of the third party servers. To add more security and reduce the risk of with a new extension called Password Checkup tool was launched on February 5.
In this extension, they provide the same data leak protection for not only Google apps and sites but also all third party accounts. The extension is filled with over 4 billion username and password credentials. While entering username and password, this extension runs a query over those credentials and if find the extension will automatically show the warning message to change the password immediately.
Using this extension, no one can identify or know your password even Google. Google develop this tool with the help of cryptography researches from Google and Stanford University.
Cross Account Protection
Even though your account is protected in all ways, hackers can able to crack it in rare cases. Mainly sites with Google authentication. This Password Checkup tool is useless at that time. For this, Google uses Cross Account Protection. From this feature, Google will tell the security events happened on your account like when and where the account was hacked. Aware that, Google only share information with the user's knowledge.
This was developed with the help of Adobe, OpenID Foundation and Internet Engineering Task Force (IETF).