Google Chrome has added support for Windows 10 Dark Mode support to Google Chrome. The developers removed the Windows code so they could continue to work on the project. Windows developers needed a missing laptop to test the implementation of the Dark Mode feature. Google does not allow Windows devices at its HQ due to security reasons and Windows-related dev work usually gets done via a virtual machine. Chrome Canary can now be in a pseudo Dark Mode on the desktop using a shortcut to open Chrome Canary. This mode is still in development and is very far from complete and you should not expect a working Dark Mode.
Source: https://www.bleepingcomputer.com/news/google/windows-10-dark-mode-in-chrome-delayed-by-missing-laptop/