How add circle Shape in Google maps custom icon?

//adapted from http://gmaps-samples-v3.googlecode.com/svn/trunk/overlayview/custommarker.html
function CustomMarker(latlng, map, imageSrc) {
  this.latlng_ = latlng;
  this.imageSrc = imageSrc;
  // Once the LatLng and text are set, add the overlay to the map.  This will
  // trigger a call to panes_changed which should in turn call draw.
  this.setMap(map);
}

CustomMarker.prototype = new google.maps.OverlayView();

CustomMarker.prototype.draw = function() {
  // Check if the div has been created.
  var div = this.div_;
  if (!div) {
    // Create a overlay text DIV
    div = this.div_ = document.createElement('div');
    // Create the DIV representing our CustomMarker
    div.className = "customMarker"


    var img = document.createElement("img");
    img.src = this.imageSrc;
    div.appendChild(img);
    var me = this;
    google.maps.event.addDomListener(div, "click", function(event) {
      google.maps.event.trigger(me, "click");
    });

    // Then add the overlay to the DOM
    var panes = this.getPanes();
    panes.overlayImage.appendChild(div);
  }

  // Position the overlay 
  var point = this.getProjection().fromLatLngToDivPixel(this.latlng_);
  if (point) {
    div.style.left = point.x + 'px';
    div.style.top = point.y + 'px';
  }
};

CustomMarker.prototype.remove = function() {
  // Check if the overlay was on the map and needs to be removed.
  if (this.div_) {
    this.div_.parentNode.removeChild(this.div_);
    this.div_ = null;
  }
};

CustomMarker.prototype.getPosition = function() {
  return this.latlng_;
};

var map = new google.maps.Map(document.getElementById("map"), {
  zoom: 17,
  center: new google.maps.LatLng(37.77088429547992, -122.4135623872337),
  mapTypeId: google.maps.MapTypeId.ROADMAP
});

var data = [{
  profileImage: "http://www.gravatar.com/avatar/d735414fa8687e8874783702f6c96fa6?s=90&d=identicon&r=PG",
  pos: [37.77085, -122.41356],
}, {
  profileImage: "http://placekitten.com/90/90",
  pos: [37.77220, -122.41555],
}]

for (var i = 0; i < data.length; i++) {
  new CustomMarker(new google.maps.LatLng(data[i].pos[0], data[i].pos[1]), map, data[i].profileImage)
}

.customMarker {
  position: absolute;
  cursor: pointer;
  background: #424242;
  width: 100px;
  height: 100px;
  /* -width/2 */
  margin-left: -50px;
  /* -height + arrow */
  margin-top: -110px;
  border-radius: 50%;
  padding: 0px;
}

.customMarker:after {
  content: "";
  position: absolute;
  bottom: -10px;
  left: 40px;
  border-width: 10px 10px 0;
  border-style: solid;
  border-color: #424242 transparent;
  display: block;
  width: 0;
}

.customMarker img {
  width: 90px;
  height: 90px;
  margin: 5px;
  border-radius: 50%;
}

<script src="https://maps.google.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<div id="map" style="width: 640pxpx; height: 480px;">map div</div>