Google is testing a new feature in the Chrome Canary builds that allows you to change the colors used by various user interface elements of the browser. This allows users to make the browser and its New Tab Page a colorful mess that some may find amusing, while others find painful. Google is only providing four choices for the Color and Theme section, but I would expect as time goes on this will be changed to allow you to customize it as you want. The color theme selected in the “Color and Theme”” section will also be used in any other tab you have open when visiting sites.”
Source: https://www.bleepingcomputer.com/news/google/google-chrome-canary-flag-makes-the-browser-a-colorful-mess/