$wp_customize->add_setting( 'cd_button_text' , array(
    'default'     => 'Come On In',
    'transport'   => 'postMessage',
) );

$wp_customize->add_control( 'cd_button_text', array(
    'label' => 'Button Text',
'section'	=> 'cd_button',
'type'	 => 'text',
) );