[WebUI TaskManager] Fix JS check nits in chrome/browser/resources/task_manager.

chrome/browser/resources/task_manager/preload.js

 // Copyright (c) 2012 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.
 
 // Defines global variables.
 var commands = TaskManagerCommands;
 var taskmanager = undefined;  // This will be instantiated in main.js.
 
 /**
  * Invoked when a range of items has changed.
+ * @param {Integer} start The start position of tasks to be changed
+ * @param {Integer} length The length of tasks to be changed
+ * @param {Array of task} tasks The array of updated task
  */
 function taskChanged(start, length, tasks) {
   var task = {type: 'change', start: start, length: length, tasks: tasks};
 
   if (taskmanager) taskmanager.processTaskChange(task);
 }
 
 // Cached list of enabled columns to prevent frequent access to localStorage.
 var cachedEnabledColumns;
 
 /**
- * Returns the dictionary which contains the list of columns and whether each
- * column is enabled or not.
+ * @return {Dictionary} the dictionary which contains the list of columns and
+ * whether each column is enabled or not.
  */
 function getEnabledColumns() {
   // Use the cache after the second time since access to localStorage is slow.
   if (cachedEnabledColumns)
     return cachedEnabledColumns;
 
   var json = window.localStorage.getItem(ENABLED_COLUMNS_KEY);
   try {
     cachedEnabledColumns = JSON.parse(json) || {};
   } catch (e) {
     cachedEnabledColumns = {};
   }
   for (var i = 0; i < DEFAULT_COLUMNS.length; i++) {
     if (typeof(cachedEnabledColumns[DEFAULT_COLUMNS[i][0]]) == 'undefined')
       cachedEnabledColumns[DEFAULT_COLUMNS[i][0]] = DEFAULT_COLUMNS[i][3];
   }
   return cachedEnabledColumns;
 }
 
 /**
- * Returns whether the given column (at |columnId|) is enabled or not.
+ * @return {Boolean} the given column (at |columnId|) is enabled or not.
+ * @param {String} columnId The ID of the collumn to be checked.
  */
 function isColumnEnabled(columnId) {
   return (getEnabledColumns())[columnId];
 }
 
 /**
- * Sets whether the given column is enabled or not.
+ * Sets the given column either enabled or disabled.
+ * @param {String} columnId The ID of the collumn to be set.
+ * @param {Boolean} newChecked True, to set the column enable. False otherwise.
  */
 function setColumnEnabled(columnId, newChecked) {
   commands.setUpdateColumn(columnId, newChecked);
   cachedEnabledColumns[columnId] = newChecked;
   var json = JSON.stringify(cachedEnabledColumns);
   window.localStorage.setItem(ENABLED_COLUMNS_KEY, json);
 }
 
 // Enable the taskmanager model before the loading of scripts.
-(function () {
+(function() {
   for (var i = 0; i < DEFAULT_COLUMNS.length; i++) {
     var columnId = DEFAULT_COLUMNS[i][0];
     if (isColumnEnabled(columnId))
       commands.setUpdateColumn(columnId, true);
   }
   commands.enableTaskManager();
   commands.setUpdateColumn('canInspect', true);
   commands.setUpdateColumn('canActivate', true);
 })();