Define externs for DatePickerCtrl.
@@ -1298,3 +1298,15 @@ md.$panel.MdPanelAnimation.prototype.closeTo = function(closeTo) {};
* @return {!md.$panel.MdPanelAnimation}
*/
md.$panel.MdPanelAnimation.prototype.withAnimation = function(cssClass) {};
+
+/******************************************************************************
+ * DatePickerCtrl
+ *****************************************************************************/
+
+/** @interface */
+md.DatePickerCtrl = function() {};
+
+/**
+ * @param {Date=} opt_date
+ */
+md.DatePickerCtrl.prototype.updateErrorState = function(opt_date) {};
