Ed Felten's article on this from a couple of months ago provides an excellent analysis.
https://freedom-to-tinker.com/2017/06/28/european-authoritie...
"At this point, I need to put some of my cards on the table and admit that I know more about this topic, having worked on the FTC’s investigation which asked some of the same questions. But that investigation was confidential, for good reasons, and I will not violate that confidentiality. All I’ll say is that the FTC had the legal power to compel answers to factual questions about Google’s practices (and an obligation to keep the answers confidential) and, having conducted a thorough investigation, the FTC decided not to bring a case against Google."