Install using your favorite plugin manager.
To install using Vundle, add the following to your vimrc:
Plugin 'google/vim-colorscheme-primary'
To set Primary as your default color scheme, add these lines to your .vimrc:
syntax enable
set t_Co=256
set background=light
colorscheme primary
For dark mode, use set background=dark
instead:
syntax enable
set t_Co=256
set background=dark
colorscheme primary
See doc/colorscheme-primary.txt for detailed instructions and additional options.
Disclaimer: This is not an official Google product (experimental or otherwise), it is just code that happens to be owned by Google.