Google I/O — Mountain View’s biggest event of the year — returns to San Francisco later this week for an event highlighted by a massive three-hour keynote presentation on Wednesday. The annual conference is ostensibly aimed at developers, who will spend three days in sessions learning how to build for Android, Chrome, and a host of other Google products and services. Google’s new head of mobile, Sundar Pichai, has said this year’s event will not be as focused on consumer products as in years past. There won’t be “much in the way of launches of new products or a new operating system,” Pichai told Wired. That may be the case, but we still expect Wednesday’s keynote to be stacked with product news. Big announcements at I/O have become a company tradition. In 2011, the first Chromebooks were announced; last year, Google gave Glass its public debut with a spectacular livestreamed skydive onto the roof of Moscone Center — not once, but twice.