Who could help me?
I have just switched to a custom ROM of MIUI for my Galaxy S2 and installed the Google service as shown below but I could not have Google contact which is very important.
Update 19/12: Solutions
Thanks to the articles on MIUI forum as stated in the chosen answer in the comment:
We need to search for a Google Installer in MIUI Market (which I already installed but didn’t install all services of Google). It has a Google Contact Sync, it is written in Chinese but you can try, it will ask you to install and you will see as first image below. Then everything is fine for sync.