Google Maps APIで外部のKMLファイルを表示するときの注意点 ref: http://qiita.com/comocc/items/3fc93859cb3d1955398f

file0.js

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 11,
    center: {lat: 35.681269, lng: 41.876}
  });

  var ctaLayer = new google.maps.KmlLayer({
    url: 'http://localhost/tokyost.kml', // NG
    map: map
  });
}

file1.txt

https://drive.google.com/file/d/0B9BZNJJL012qTjVWT0FQdlRvbFU/view?usp=sharing

file2.js

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 11,
    center: {lat: 35.681269, lng: 41.876}
  });

  var ctaLayer = new google.maps.KmlLayer({
      url: 'https://drive.google.com/file/d/0B9BZNJJL012qTjVWT0FQdlRvbFU/view?usp=sharing', // NG
      map: map
  });
}

file3.js

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 11,
    center: {lat: 35.681269, lng: 41.876}
  });

  var ctaLayer = new google.maps.KmlLayer({
    url: 'https://sites.google.com/a/foobarbaz/test/tokyost.kml',
    map: map
  });
}