Add a pref checkbox to enable/disable screen lock for ChromeOs.

chrome/browser/resources/options/personal_options.js

Index: chrome/browser/resources/options/personal_options.js
diff --git a/chrome/browser/resources/options/personal_options.js b/chrome/browser/resources/options/personal_options.js
index c0871cebf450bb4b00db7e0ca0e905457b6b92bc..357f5affb178836629df45dc523da47a0e29289a 100644
--- a/chrome/browser/resources/options/personal_options.js
+++ b/chrome/browser/resources/options/personal_options.js
@@ -94,6 +94,10 @@ cr.define('options', function() {
           chrome.send('themesGallery');
         }
       }
+
+      if (cr.isChromeOS) {
+        chrome.send('loadAccountPicture');
+      }
     },
 
     syncStatusCallback_: function(statusString) {
@@ -148,6 +152,10 @@ cr.define('options', function() {
     PersonalOptions.getInstance().setClassicThemeButtonEnabled_(enabled);
   };
 
+  PersonalOptions.setAccountPicture = function(image) {
+    $('account-picture').src = image;
+  }
+
   // Export
   return {
     PersonalOptions: PersonalOptions