WordPress Custom Theme Selector and Custom Container Selector

customizer.php

<?php
  function wpb_customize_register($wp_customize){
    /*
    *
    * SHOWCASE THEME SELECTOR
    *
    */
    $wp_customize->add_setting('theme_selector', array(
      'default'   => _x('bootstrap', 'kevinurielfonsecav2'),
      'type'      => 'theme_mod'
    ));

    $wp_customize->add_control( new WP_Customize_Control($wp_customize, 'theme_selector', array(
    'label'       => __( 'Select Theme Name', 'kevinurielfonsecav2' ), //Admin-visible name of the control
    'description' => __( 'Using this option you can change the theme colors' ),
    'priority'    => 90, //Determines the order this control appears in for the specified section
    'section'     => 'title_tagline', //ID of the section this control should render in (can be one of yours, or a WordPress default section)
    'type'        => 'select',
    'choices'     => array(
        'bootstrap'   =>  'Default',
        'cerulean'    =>  'Cerulean',
        'cosmo'       =>  'Cosmo',
        'cyborg'      =>  'Cyborg',
        'darkly'      =>  'Darkly',
        'flatly'      =>  'Flatly',
        'journal'     =>  'Journal',
        'litera'      =>  'Litera',
        'lumen'       =>  'Lumen',
        'lux'         =>  'Lux'
      )
    )));
    /*
    *
    * SHOWCASE THEME CONTAINER SELECTOR
    *
    */
    $wp_customize->add_setting('theme_container', array(
      'default'   => _x('container', 'kevinurielfonsecav2'),
      'type'      => 'theme_mod'
    ));

    $wp_customize->add_control( new WP_Customize_Control($wp_customize, 'theme_container', array(
    'label'       => __( 'Select Theme Container', 'kevinurielfonsecav2' ), //Admin-visible name of the control
    'description' => __( 'Using this option you can change the theme container' ),
    'priority'    => 90, //Determines the order this control appears in for the specified section
    'section'     => 'title_tagline', //ID of the section this control should render in (can be one of yours, or a WordPress default section)
    'type'        => 'select',
    'choices'     => array(
        'container'          => 'Container',
        'container-fluid'    => 'Container Fluid',
      )
    )));
// end of customizer function //
  }
  add_action('customize_register', 'wpb_customize_register');
?>