Last year, Chrome made Flash ads click-to-play; now, Google is trying to kill off Flash completely.
Starting with Chrome 53, due out early next month, the browser will automatically block tiny and non-visible Flash content, such as tracking and fingerprint cookies that are notoriously hard to shake off. Then, with Chrome 55 in December, Flash will be deprecated entirely, with exceptions for "sites which only support Flash." In both cases HTML5 is expected to take up the reins.
The changes in Chrome 53 are mostly targeted at behind-the-scenes Flash widgets that many sites use for tracking and analytics purposes. Best-case these non-visible elements can slow down your browsing experience, worst-case they might cause stability issues or reduce battery life on mobile devices. Google says that publishers are in the process of moving these widgets over to HTML5.