Background Color not being set in WP Customizer

Also I modified two things

One:

$wp_customize->add_setting(
    // $id
    'header_background_color',
    // $args
    array(
        'default'           => '',
        'type'              => 'theme_mod',
        'capability'        => 'edit_theme_options',
        'sanitize_callback' => 'sanitize_hex_color',
        'transport'         => 'postMessage'
    )
);

Two:

$wp_customize->add_control(
    new WP_Customize_Color_Control(
        // $wp_customize object
        $wp_customize,
        // $id
        'header_background_color',
        // $args
        array(
            'settings'      => 'header_background_color',
            'section'       => 'sk_section_header',
            'label'         => __( 'Header Background Color', 'theme-slug' ),
            'description'   => __( 'Select the background color for header.', 'theme-slug' ),
            'type'          => 'color',

        )
    )
);