Configure the color of the browser's theme

This policy allows admins to configure the color of Brave's theme. The input string should be a valid hex color string matching the format "#RRGGBB". Setting the policy to a valid hex color causes a theme based on that color to be automatically generated and applied to the browser. Users won't be able to change the theme set by the policy. Leaving the policy unset lets users change their browser's theme as preferred. Example value: #FFFFFF