There are many phishing websites, that appear to be authentic but are not so. They are camouflaged as real websites, and often ask you to enter your Gmail logic credentials in order to login to the website. When you do it, the credentials are stolen. If such things happen from now on, Google will warn its users, and will warn the user to change the password.
Google will be scrutinizing where you are using your Google username and passwords. It will not access your password but can detect if you have entered the credentials anywhere. Google can do this using trial and tested encryption techniques, which allows it to check a single password against a large number of stolen credentials without seeing the plain text.
Google wrote in a blog post, “When you sign in to a website, Chrome will send a strongly hashed copy of your username and password to Google encrypted with a secret key only known to Chrome. No one, including Google, is able to derive your username or password from this encrypted copy.”
Google converts the password, you enter, by passing it through an algorithm, into a combination of alphabets and numbers. This is called hash. If a hash match is found, it will inform you to change your credentials.
