Memory leak when clusters are frequently redrawn

Version: 2.0.9

I have created simple map dashboard which shows currently active customers.
When customer connects new marker is added to the clusterer and when customer 
disconnects marker is removed from it.
In order to display this changes marker clusterer are redrawn every second.

Memory leak related to fix for Issue 157

In ClusterIcon.onAdd method listener for "bounds_changed" event is created, but 
never cleared after in onRemove function

Solution/Workaround:
1 Add property to save listener reference in it (boundsChangedListenerRef_) to 
ClusterIcon

function ClusterIcon(cluster, styles) {
  cluster.getMarkerClusterer().extend(ClusterIcon, google.maps.OverlayView);

  this.cluster_ = cluster;
  this.styles_ = styles;
  this.center_ = null;
  this.div_ = null;
  this.sums_ = null;
  this.visible_ = false;
  this.boundsChangedListenerRef_ = null; // Property for "bounds_changed" event listener reference

  this.setMap(cluster.getMap()); // Note: this causes onAdd to be called
}

2 In ClusterIcon.onAdd method save reference to newly created listener
  // Fix for Issue 157
  if (this.boundsChangedListenerRef_) {
      google.maps.event.removeListener(this.boundsChangedListenerRef_);
  }

  this.boundsChangedListenerRef_ = google.maps.event.addListener(this.getMap(), "bounds_changed", function () {
    cDraggingMapByCluster = cMouseDownInCluster;
  });

3 In ClusterIcon.onRemove method remove listener, which is not necessary anymore
  if (this.boundsChangedListenerRef_) {
    google.maps.event.removeListener(this.boundsChangedListenerRef_);
    this.boundsChangedListenerRef_ = null;
  }

Original issue reported on code.google.com by Andrejs.Bedenko on 6 Jan 2014 at 3:25

Merged into: #265

frank0051 / google-maps-utility-library-v3

Memory leak when clusters are frequently redrawn #286