Custom_Background::init() WordPress Method

	public function init() {
		$page = add_theme_page( __( 'Background' ), __( 'Background' ), 'edit_theme_options', 'custom-background', array( $this, 'admin_page' ) );
		if ( ! $page ) {
			return;
		}

		add_action( "load-{$page}", array( $this, 'admin_load' ) );
		add_action( "load-{$page}", array( $this, 'take_action' ), 49 );
		add_action( "load-{$page}", array( $this, 'handle_upload' ), 49 );

		if ( $this->admin_header_callback ) {
			add_action( "admin_head-{$page}", $this->admin_header_callback, 51 );
		}
	}