Align signatures of attributeChangedCallback

lib/elements/dom-bind.js

@@ -64,9 +64,13 @@ export class DomBind extends domBindBase {
 
   /**
    * @override
+   * @param {string} name Name of attribute that changed
+   * @param {?string} old Old attribute value
+   * @param {?string} value New attribute value
+   * @param {?string} namespace Attribute namespace.
    * @return {void}
    */
-  attributeChangedCallback() {
+  attributeChangedCallback(name, old, value, namespace) {
     // assumes only one observed attribute
     this.mutableData = true;
   }

lib/mixins/disable-upgrade-mixin.js

@@ -67,8 +67,8 @@ export const DisableUpgradeMixin = dedupingMixin((base) => {
      * @param {string} name Attribute name.
      * @param {?string} old The previous value for the attribute.
      * @param {?string} value The new value for the attribute.
-     * @param {?string=} namespace The XML namespace for the attribute.
-     * @return {undefined}
+     * @param {?string} namespace The XML namespace for the attribute.
+     * @return {void}
      */
     attributeChangedCallback(name, old, value, namespace) {
       if (name == DISABLED_ATTR) {

lib/mixins/properties-changed.js

@@ -426,7 +426,7 @@ export const PropertiesChanged = dedupingMixin(
      * @param {string} name Name of attribute that changed
      * @param {?string} old Old attribute value
      * @param {?string} value New attribute value
-     * @param {?string=} namespace Attribute namespace.
+     * @param {?string} namespace Attribute namespace.
      * @return {void}
      * @suppress {missingProperties} Super may or may not implement the callback
      * @override