How to use habakiri_theme_mods_defaults

.php

<?php
function habakiri_child_theme_setup() {
	class Habakiri extends Habakiri_Base_Functions {
		public function __construct() {
			parent::__construct();
			
			add_action( 'habakiri_theme_mods_defaults', array( $this, 'habakiri_theme_mods_defaults' ) );
		}
		
		/**
		 * Set default values of customizer
		 * 
		 * @param array $pre_defaults
		 * @return array
		 */
		public function habakiri_theme_mods_defaults( $pre_defaults ) {
			$defaults = shotcode_atts(
				$pre_defaults,
				array(
					'link_color'    => '#f00',
					'blog_template' => 'left-sidebar',
				)
			);
			return $defaults;
		}
	}
}
add_action( 'after_setup_theme', 'habakiri_child_theme_setup' );