Add ARC version to help and version pages

chrome/browser/resources/help/help_page.js

Index: chrome/browser/resources/help/help_page.js
diff --git a/chrome/browser/resources/help/help_page.js b/chrome/browser/resources/help/help_page.js
index e4a6afa23af95fe5c037f05d3c9f0b89dfe56ba8..c2eb0d5a9fe1eb295fdd72ba16f6323973f141e3 100644
--- a/chrome/browser/resources/help/help_page.js
+++ b/chrome/browser/resources/help/help_page.js
@@ -505,6 +505,18 @@ cr.define('help', function() {
     },
 
     /**
+     * @param {string} version Version of ARC.
+     * @private
+     */
+    setARCVersion_: function(version) {
+      if (!cr.isChromeOS)
+        console.error('ARC version unsupported on non-CrOS');
+
+      $('arc-version').parentNode.hidden = (version == '');
+      $('arc-version').textContent = version;
+    },
+
+    /**
      * @param {string} firmware Firmware on Chrome OS.
      * @private
      */
@@ -670,6 +682,10 @@ cr.define('help', function() {
     HelpPage.getInstance().setOSVersion_(version);
   };
 
+  HelpPage.setARCVersion = function(version) {
+    HelpPage.getInstance().setARCVersion_(version);
+  };
+
   HelpPage.setOSFirmware = function(firmware) {
     HelpPage.getInstance().setOSFirmware_(firmware);
   };