Google's Chromebooks have had built-in screenshot functionality from the beginning, but somewhat recent hints that a change to that function that allows Chromebooks in tablet mode to ape Android devices have manifested in the form of an Android-like screenshot functionality in the Chrome OS dev channel. The function allows Chromebook owners to take a screenshot on their device by simply pressing the power button and volume down at the same time, but it will only work while the device is in tablet mode. Screenshots taken in laptop mode will have to be done the usual way, via the software. There has been no word thus far on when this feature is going to be hitting the stable channel.
The new feature is, naturally, only available on convertible Chromebooks for now, and can only be used while in tablet mode. The code for the feature explicitly specifies this requirement, though it's entirely possible that a similar button combination could come to laptop mode. This feature will most likely be the main way of taking screenshots on detachable Chromebooks and Chrome OS tablets, once such devices begin appearing. There have already been countless hints that both categories are coming in the near future.
Google has been quite busy lately making Chrome OS work better in tablet mode, putting more and more emphasis on that aspect of the experience leading up to the release of the premium Pixelbook, which uses a convertible form factor and represents the best experience in the Chrome OS world for the time being, according to Google. The company has also scored a patent for a laptop with two screens, not unlike the Lenovo Yoga Book. There was wide speculation that Lenovo would release a Chrome OS version of that device, and the fact that Google seems to be planning a similar device of its own may well be the reason that such a device never came to be. This change will affect a number of the best-reviewed and most popular Chromebooks currently out, such as Samsung's Chromebook Plus and Pro, and Acer's durable and well-specced new Spin 11 convertible.