Add an optional set_hook argument to defineProperty.

chrome/browser/resources/shared/js/cr.js

Index: chrome/browser/resources/shared/js/cr.js
diff --git a/chrome/browser/resources/shared/js/cr.js b/chrome/browser/resources/shared/js/cr.js
index 6686269d897f1ddd7c7f396529506bdbf3e49e4b..3786d7568182213d6c8e6e24c254da3b6279dc35 100644
--- a/chrome/browser/resources/shared/js/cr.js
+++ b/chrome/browser/resources/shared/js/cr.js
@@ -170,9 +170,11 @@ const cr = (function() {
    *     for.
    * @param {cr.PropertyKind} kind The kind of property we are getting the
    *     setter for.
+   * @param {function():void} opt_set_hook A function to run after the property
+   *     is set, but before the propertyChange event is fired.
    * @return {function(*):void} The function to use as a setter.
    */
-  function getSetter(name, kind) {
+  function getSetter(name, kind, opt_set_hook) {

[arv (Not doing code reviews), 2011/02/03 21:52:08]

opt_setHook

[nduca, 2011/02/04 01:31:32]

Done.

     switch (kind) {
       case PropertyKind.JS:
         var privateName = name + '_';
@@ -180,6 +182,8 @@ const cr = (function() {
           var oldValue = this[privateName];
           if (value !== oldValue) {
             this[privateName] = value;
+            if (opt_set_hook)
+              opt_set_hook.apply(this);

[arv (Not doing code reviews), 2011/02/03 21:52:08]

I was thinking that it should pass the new value for convenience.

opt_setHook.call(this, value);

[nduca, 2011/02/04 01:31:32]

Done.

             dispatchPropertyChange(this, name, value, oldValue);
           }
         };
@@ -189,6 +193,8 @@ const cr = (function() {
           var oldValue = this[name];
           if (value !== oldValue) {
             this.setAttribute(name, value);
+            if (opt_set_hook)
+              opt_set_hook.apply(this);
             dispatchPropertyChange(this, name, value, oldValue);
           }
         };
@@ -201,6 +207,8 @@ const cr = (function() {
               this.setAttribute(name, name);
             else
               this.removeAttribute(name);
+            if (opt_set_hook)
+              opt_set_hook.apply(this);
             dispatchPropertyChange(this, name, value, oldValue);
           }
         };
@@ -213,9 +221,11 @@ const cr = (function() {
    * @param {!Object} The object to define the property for.
    * @param {string} The name of the property.
    * @param {cr.PropertyKind=} opt_kind What kind of underlying storage to use.
-   * @param {*} opt_defaultValue The default value.
+   * @param {*} opt_default The default value.
+   * @param {function():void} opt_set_hook A function to run after the property
+   *     is set, but before the propertyChange event is fired.
    */
-  function defineProperty(obj, name, opt_kind, opt_default) {
+  function defineProperty(obj, name, opt_kind, opt_default, opt_set_hook) {
     if (typeof obj == 'function')
       obj = obj.prototype;
 
@@ -231,7 +241,7 @@ const cr = (function() {
     }
 
     if (!obj.__lookupSetter__(name)) {
-      obj.__defineSetter__(name, getSetter(name, kind));
+      obj.__defineSetter__(name, getSetter(name, kind, opt_set_hook));
     }
   }