Google is gearing up for a summer of heated antitrust battles: Here's a guide to the various investigations and regulatory threats Google is facing (GOOG, GOOGL)

· Google is preparing for a long antitrust summer as multiple investigations into its business come to a head. 
· CEO Sundar Pichai will testify in front of Congress later this month alongside the CEOs of Apple, Amazon, and Facebook.
· But Google is being probed by other investigations into its advertising and search...