Adding custom Wordpress theme options to customize page.

functions.php

<?php
/**
 * Taken from tutorial at http://ottopress.com/2012/theme-customizer-part-deux-getting-rid-of-options-pages/
 * and http://ottopress.com/2012/making-a-custom-control-for-the-theme-customizer/
 */

add_action( 'customize_register', 'theme_customize_register' );
function theme_customize_register($wp_customize) {

    //add a textarea control to the wp_customize
    class Customize_Textarea_Control extends WP_Customize_Control {
        public $type = 'textarea';
     
        public function render_content() {
            ?>
            <label>
            <span class="customize-control-title"><?php echo esc_html( $this->label ); ?></span>
            <textarea rows="5" style="width:100%;" <?php $this->link(); ?>><?php echo esc_textarea( $this->value() ); ?></textarea>
            </label>
            <?php
        }
    }

    //Social Links Section
    $wp_customize->add_section( 'theme_social_links', array(
        'title'          => 'Social Links',
        'priority'       => 35,
    ) );
    
    //LinkedIn Profile Url
    $wp_customize->add_setting( 'linkedin_url', array(
        'default'        => '',
    ) );
 
    $wp_customize->add_control( 'linkedin_url', array(
        'label'   => 'LinkedIn',
        'section' => 'theme_social_links',
        'type'    => 'text',
    ) );

    //Google+ Profile Url
    $wp_customize->add_setting( 'googleplus_url', array(
        'default'        => '',
    ) );
 
    $wp_customize->add_control( 'googleplus_url', array(
        'label'   => 'Google+',
        'section' => 'theme_social_links',
        'type'    => 'text',
    ) );

    //Twitter Profile Url
    $wp_customize->add_setting( 'twitter_url', array(
        'default'        => '',
    ) );
 
    $wp_customize->add_control( 'twitter_url', array(
        'label'   => 'Twitter',
        'section' => 'theme_social_links',
        'type'    => 'text',
    ) );

    //Address and Contact Section
    $wp_customize->add_section( 'theme_contact', array(
        'title'          => 'Contact Info',
        'priority'       => 36,
    ) );
    
    //Main Company Phone
    $wp_customize->add_setting( 'company_phone', array(
        'default'        => '',
    ) );
 
    $wp_customize->add_control( 'company_phone', array(
        'label'   => 'Company Phone',
        'section' => 'theme_contact',
        'type'    => 'text',
    ) );

    //Company Email
    $wp_customize->add_setting( 'company_email', array(
        'default'        => '',
    ) );
 
    $wp_customize->add_control( 'company_email', array(
        'label'   => 'Company Email',
        'section' => 'theme_contact',
        'type'    => 'text',
    ) );

    //Company Address
    $wp_customize->add_setting( 'company_address', array(
        'default'        => '',
    ) );
 
    $wp_customize->add_control( new Customize_Textarea_Control( $wp_customize, 'company_address', array(
        'label'   => 'Address',
        'section' => 'theme_contact',
        'settings'   => 'company_address',
    ) ) );
}

?>

page-custom.php

<a class="button button--social" href="<?php echo get_theme_mod( 'linkedin_url', 'default_value' ); ?>" title="LinkedIn Profile">LinkedIn Profile</a>