Google looks like it’s finally adding a built-in dark theme into Chrome OS, but thus far, the feature is only experimental in Canary build…
Perhaps in the not-too-distant future, Chrome OS will sport its own dark mode. This, as Google continues to test the option on its Canary channel. If it comes to fruition, the dark theme treatment will follow other Google products, such as Gmail, Google Calendar, Google Fit, Keep Notes, and others. However, there’s no official word on when to expect the tool to reach stable release.
Chrome OS Dark Mode Support Under Testing
Right now, the only way to access Chrome OS’s dark theme is to switch a Chromebook (or Chromebox) over to Google’s special developer mode — which isn’t the same as the Chrome OS Developer channel. Then, install the Canary channel onto the device. Next, it’s necessary to activate a flag. Type in “chrome://flags/#enable-force-dark and chrome://flags/#enable-webui-dark-mode” into the URL bar and turn it on.
Of course, Google warns enabling developer mode, along with installing and running Canary, might trigger unwanted consequences. This is considered an experimental experience, so it might only partially work or not work at all.