Implemented a "Last Updated" field for the about page of Chrome OS.

chrome/browser/resources/help/help.js

Index: chrome/browser/resources/help/help.js
diff --git a/chrome/browser/resources/help/help.js b/chrome/browser/resources/help/help.js
index 28910ff639aed2c935db3127a6663c2d67481fbe..ac3e93d67a95ddf85cc68603d8c525c3cb016643 100644
--- a/chrome/browser/resources/help/help.js
+++ b/chrome/browser/resources/help/help.js
@@ -213,6 +213,16 @@ cr.define('help', function() {
     setReleaseChannel_: function(channel) {
       chrome.send('setReleaseTrack', [channel]);
     },
+
+    /**
+     * Sets the value of the "Last Updated" field of the "More Info" section.
+     * @param {String} lastUpdated The date of the last update.
+     * @private
+     */
+    setLastUpdated_: function(lastUpdated) {
+      $('last-updated-container').classList.remove('empty');
+      $('last-updated').textContent = lastUpdated;
+    },
   };
 
   HelpPage.setUpdateStatus = function(status, message) {
@@ -251,6 +261,10 @@ cr.define('help', function() {
     HelpPage.getInstance().setReleaseChannel_(channel);
   };
 
+  HelpPage.setLastUpdated = function(lastUpdated) {
+    HelpPage.getInstance().setLastUpdated_(lastUpdated);
+  }
+
   // Export
   return {
     HelpPage: HelpPage