A new commit has been pushed to the official Chromium Gerrit Code Review which seems to indicate that the Backdrop wallpaper functionality found in Chromecast devices will soon make its way to Chrome OS. What's more, it appears that will be part of a newly redesigned wallpaper picker for the Chrome-based platform. In fact, by enabling a flag in the Chrome OS hidden settings menu, found by navigating to "chrome://flags," users can already take a look at the new feature on some Chromebooks. Of course, the feature won't work exactly as it does on Chromecast but does pull from the same Google Backdrop service. Instead, it seems to be a replacement for the previously implemented "Surprise Me" option which automatically randomly pulled images for the wallpaper. However, there's going to be a lot of similarities and almost certainly a lot of the same images available.
Breaking down how the feature will work, it's going to be part of a very different UI which appears to be much more touch-friendly. That makes sense since there are quite a few touch-enabled devices on the way and some which will be "only touch" by default. As shown in the screenshots below, users will still have a category to choose from and a range of images. However, many or most of those will be pulled from Backdrop and there's even a refresh button along the top, next to the image's title and author or description. Residing next to that, there's an "explore" link-style button for finding even more images. However, there's also a "Daily Refresh" toggle option in any given category which will automatically cycle through the category on a daily basis. Users can select a folder on the Chromebook itself, as was an option with the previous wallpaper picker. With that said, there's a chance that further functionality will be added over time and before the final release. So users may have the option to change the frequency of wallpaper changes or choose a Google Drive folder when it launches or with a future update.
In the meantime, as mentioned above, it's already possible to access the new wallpaper picker in the Stable Channel of Chrome OS. That's the channel most users are already on by default, although there are a few bugs with the daily refresh feature. Namely, that seems to not always match up with the chosen category, as of this writing. Users only need to navigate to the "chrome://flags" URL and search for "new wallpaper." The hidden setting to "Enable new wallpaper picker" should be among those listed and the new U.I. will be available after setting that to "enabled" and performing a restart. Then, holding the alt-key and clicking the current wallpaper screen will bring up an option to change the wallpaper. It's worth pointing out that a future update to the OS will most likely replace the old wallpaper picker with this one. So there's really no rush for those who don't want to deal with the bugs.