wp-includes/fonts.php:263Register the default font collections.
function _wp_register_default_font_collections() { wp_register_font_collection( 'google-fonts', array( 'name' => _x( 'Google Fonts', 'font collection name' ), 'description' => __( 'Install from Google Fonts. Fonts are copied to and served from your site.' ), 'font_families' => 'https://s.w.org/images/fonts/wp-7.1/collections/google-fonts-with-preview.json', 'categories' => array( array( 'name' => _x( 'Sans Serif', 'font category' ), 'slug' => 'sans-serif', ), array( 'name' => _x( 'Display', 'font category' ), 'slug' => 'display', ), array( 'name' => _x( 'Serif', 'font category' ), 'slug' => 'serif', ), array( 'name' => _x( 'Handwriting', 'font category' ), 'slug' => 'handwriting', ), array( 'name' => _x( 'Monospace', 'font category' ), 'slug' => 'monospace', ), ), ) );}Introduced in 6.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/fonts.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.