<?php
// Social Icons
add_action( 'customize_register', 'berkeley_customize_register_social' );
function berkeley_customize_register_social( $wp_customize ) {
    //Social Icons Section
    $wp_customize->add_section('berkeley_social_section',
        array(
            'title' => __('Social Icons','berkeley'),
            'priority' => 1 ,
            'panel' => 'berkeley_content_panel'
        )
    );

    //Social Icons Array
    $social_networks = array( //Redefinied in Sanitization Function.
        'none' => __('-','berkeley'),
        'facebook' => __('Facebook','berkeley'),
        'twitter' => __('Twitter','berkeley'),
        'google-plus' => __('Google Plus','berkeley'),
        'instagram' => __('Instagram','berkeley'),
        'rss' => __('RSS Feeds','berkeley'),
        'vine' => __('Vine','berkeley'),
        'vimeo-square' => __('Vimeo','berkeley'),
        'youtube' => __('Youtube','berkeley'),
        'flickr' => __('Flickr','berkeley'),
    );

    //Social Icon Controls Loop
    $social_count = count($social_networks);

    for ($x = 1 ; $x <= ($social_count - 3) ; $x++) :

        $wp_customize->add_setting(
            'berkeley_social_'.$x, array(
            'sanitize_callback' => 'berkeley_sanitize_social',
            'default' => 'none'
        ));

        $wp_customize->add_control( 'berkeley_social_'.$x, array(
            'settings' => 'berkeley_social_'.$x,
            'label' => __('Icon ','berkeley').$x,
            'section' => 'berkeley_social_section',
            'type' => 'select',
            'choices' => $social_networks,
        ));

        $wp_customize->add_setting(
            'berkeley_social_url'.$x, array(
            'sanitize_callback' => 'esc_url_raw'
        ));

        $wp_customize->add_control( 'berkeley_social_url'.$x, array(
            'settings' => 'berkeley_social_url'.$x,
            'description' => __('Icon ','berkeley').$x.__(' Url','berkeley'),
            'section' => 'berkeley_social_section',
            'type' => 'url',
            'choices' => $social_networks,
        ));

    endfor;

    function berkeley_sanitize_social( $input ) {
        $social_networks = array(
            'none' ,
            'facebook',
            'twitter',
            'google-plus',
            'instagram',
            'rss',
            'vine',
            'vimeo-square',
            'youtube',
            'flickr'
        );
        if ( in_array($input, $social_networks) )
            return $input;
        else
            return '';
    }
}