MD Settings: adjust iron-list focus row behaviors.

ui/webui/resources/js/cr/ui/focus_row.js

Index: ui/webui/resources/js/cr/ui/focus_row.js
diff --git a/ui/webui/resources/js/cr/ui/focus_row.js b/ui/webui/resources/js/cr/ui/focus_row.js
index 652b0353f61a2ab23e4fb8dda774747ac55322f6..91399fb525026b36a1021c8e2001a3cdceca057a 100644
--- a/ui/webui/resources/js/cr/ui/focus_row.js
+++ b/ui/webui/resources/js/cr/ui/focus_row.js
@@ -105,13 +105,18 @@ cr.define('cr.ui', function() {
      * to indicate they're equivalent.
      *
      * @param {string} type The type of element to track focus of.
-     * @param {string} query The selector of the element from this row's root.
+     * @param {string|HTMLElement} selectorOrElement The selector of the element
+     *    from this row's root, or the element itself.
      * @return {boolean} Whether a new item was added.
      */
-    addItem: function(type, query) {
+    addItem: function(type, selectorOrElement) {
       assert(type);
 
-      var element = this.root.querySelector(query);
+      var element;
+      if (typeof selectorOrElement == 'string')
+        element = this.root.querySelector(selectorOrElement);
+      else
+        element = selectorOrElement;

[Dan Beam, 2017/03/21 07:11:52]

why can't you just munge the argument?  because it's an argument and not
writeable?

[scottchen, 2017/03/21 20:10:33]

Could you give me an example of how you'd do the munging in this case?

[Dan Beam, 2017/03/21 20:51:56]

I didn't see that there's a bunch of uses of |element| after this (otherwise I
would've just told you to overwrite selectorOrElement), but this is mildly
simpler if it compiles.

  if (typeof selectorOrElement == 'string')
    selectorOrElement = this.root.querySelector(selectorOrElement);

  if (!selectorOrElement)
    return false;

  var element = assertInstanceOf(selectorOrElement, Element);

       if (!element)
         return false;