About a month ago we reported Google was working on a dark theme for Chrome, in preparation for a wider night mode throughout Android Q. Although this was a very anticipated feature, we expected it would only darken the menus and navigation bar but still render web pages in their original colors. This was before our colleagues over at 9to5Google discovered the browser is actually able to alter a site's design and display it in a darker skin.
Chrome's dark mode is enabled through a new feature flag, #enable-android-web-contents-dark-mode, which activates a force_dark_mode_enabled preference in the browser's engine. This will make it use a high contrast setting, altering the way some of the web page's colors are shown. Interestingly, the menu bar is not darkened, and only the background color seems to be changed, but it's likely that a separate flag will control that. The functionality is very similar to Samsung Internet's night mode, which has been around since 2017 and uses a black menu bar.
I'm not sure this mode will do justice to most sites, but I have to admit it will save battery on OLED screens and may also be easier on the eyes. If you want to give it a try, the feature is already live in Chrome Canary and is also available in WebView, just head to chrome://flags to turn it on.