Chrome OS migrators from Windows 10 may miss the ability to have the system pull the main color from their wallpaper and apply it systemwide, but recent changes in the handling of the app dock in Chrome OS indicate that they may gain that ability soon. Brandon Lall managed to spot the code, which comes in the form of an experimental flag. Currently, it's disabled by default, but when activated will pull the main color from the wallpaper algorithmically and apply it to the app dock. There is no word for the time being on when or if the feature may come to other parts of Chrome OS, although the original spotted post on Google+ did come with the image shown below and while the image does not show the feature in action per se, it does provide a conceptual preview of what it could look like in its final form.
It seems the current code is far closer to implementation that previous versions, which have been present in various forms since some of the earlier work on transitioning Chrome OS to Material Design began. Currently, the default Chrome OS theme has touches of Material Design throughout, but has not yet made the full transition. Users who are not happy with that look cannot currently match up their own wallpaper to the rest of the system automatically, but can take advantage of the same widely populated theme store that users of the Chrome browser can access, though some Chrome themes may not work properly across all of Chrome OS.
Chrome OS' customizability is a bit on the short side at the moment, and this change, when it rolls out, will go a long way towards helping to bridge the gap between Chrome OS and some of its more flexible contemporaries. The feature is still buried deep in the Chromium code repositories for now, but those who want to try it should be keeping an eye on the flags page of the developer builds of Chrome OS; all signs point to the feature being ready for primetime in the very near future, and successful implementation for the app dock could mean that other parts of the OS will soon get the same treatment.