The leaked usernames and passwords were not the result of a breach of Google systems. Often, these credentials are obtained through a combination of other sources. Make sure youre using a strong password unique to Google. Update your recovery options so we can reach you by phone or email if you get locked out of your account. And consider 2-step verification, which adds an extra layer of security to your account, at g.co/accountcheckup where you’ll see a list of many of the security controls at your disposal.”]
Source: https://security.googleblog.com/2014/09/cleaning-up-after-password-dumps.html