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

chrome/browser/resources/task_manager/main.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** @constructor */
 function TaskManager() { }
 
 cr.addSingletonGetter(TaskManager);
 
 /*
@@ skipping 175 matching lines @@
         'cpuUsage', 'physicalMemory', 'sharedMemory', 'privateMemory',
         'networkUsage', 'webCoreImageCacheSize', 'webCoreScriptsCacheSize',
         'webCoreCSSCacheSize', 'fps', 'sqliteMemoryUsed', 'goatsTeleported',
         'v8MemoryAllocatedSize'];
 
     for (var i in columns_sorted_by_value) {
       var column_id = columns_sorted_by_value[i];
       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);
     }
 
     var ary = this.dialogDom_.querySelectorAll('[visibleif]');
     for (var i = 0; i < ary.length; i++) {
       var expr = ary[i].getAttribute('visibleif');
       if (!eval(expr))
         ary[i].hidden = true;
@@ skipping 351 matching lines @@
   taskmanager.onTaskChange(start, length, tasks);
 }
 
 function taskRemoved(start, length) {
   // Sometimes this can get called too early.
   if (!taskmanager)
     return;
   taskmanager.onTaskRemove(start, length);
 }