WebUI TaskManager: Make sort rows including "N/A" correctly.

chrome/browser/resources/task_manager/main.js

Index: chrome/browser/resources/task_manager/main.js
diff --git a/chrome/browser/resources/task_manager/main.js b/chrome/browser/resources/task_manager/main.js
index a397ecf0cd31cbee420542c335fd4ef852a3a8c5..5df154a73a69e6fd9983d8e05c88c2708c8fa2ab 100644
--- a/chrome/browser/resources/task_manager/main.js
+++ b/chrome/browser/resources/task_manager/main.js
@@ -193,8 +193,11 @@ TaskManager.prototype = {
       var compare_func = function() {
           var value_id = column_id + 'Value';
           return function(a, b) {
-              return dm.defaultValuesCompareFunction(a[value_id][0],
-                                                     b[value_id][0]);
+              var aValues = a[value_id];
+              var bValues = b[value_id];
+              var aValue = aValues && aValues[0] || 0;
+              var bvalue = bValues && bValues[0] || 0;
+              return dm.defaultValuesCompareFunction(aValue, bvalue);
           };
       }();
       dm.setCompareFunction(column_id, compare_func);