When you open your free rewards, you will see that there is a new reward "Account merge". If you don't see that reward, you have already taken the bonus chips.

You can get that bonus if you merge your account with Facebook or Google.

It means that if you have registered your account with:

Facebook account - you will be able to merge your profile with your Google account
Google account - you will be able to merge your profile with your Facebook account
email - you will be able to merge your profile with your Facebook or Google account

You get this bonus only once!