Added class for close button image

src/infobubble.js

@@ -93,6 +93,10 @@ function InfoBubble(opt_options) {
   if (options['closeSrc'] == undefined) {
     options['closeSrc'] = this.CLOSE_SRC_;
   }
+
+  if (options['closeClass'] == undefined) {
+    options['closeClass'] = this.CLOSE_CLASS_;
+  }
 
   this.buildDom_();
   this.setValues(options);
@@ -186,6 +190,13 @@ InfoBubble.prototype.BACKGROUND_COLOR_ = '#fff';
  */
 InfoBubble.prototype.CLOSE_SRC_ = 'https://maps.gstatic.com/intl/en_us/mapfiles/iw_close.gif';
 
+/**
+ * Default close image css class
+ * @const
+ * @private
+ */
+InfoBubble.prototype.CLOSE_CLASS_ = 'close-image';
+
 /**
  * Extends a objects prototype by anothers.
  *
@@ -223,6 +234,7 @@ InfoBubble.prototype.buildDom_ = function() {
   close.style['zIndex'] = this.baseZIndex_ + 1;
   close.style['cursor'] = 'pointer';
   close.src = this.get('closeSrc');
+  close.className = this.get('closeClass');
 
   var that = this;
   google.maps.event.addDomListener(close, 'click', function() {
@@ -781,6 +793,18 @@ InfoBubble.prototype.setCloseSrc = function(src) {
 };
 InfoBubble.prototype['setCloseSrc'] = InfoBubble.prototype.setCloseSrc;
 
+/**
+ * Set the close image css class
+ *
+ * @param {string} className css class of the image used as a close icon
+ */
+InfoBubble.prototype.setCloseClass = function(className) {
+  if (className && this.close_) {
+    this.close_.className = className;
+  }
+};
+InfoBubble.prototype['setCloseClass'] = InfoBubble.prototype.setCloseClass;
+
 
 /**
  * Set the padding of the InfoBubble