Implement ephemeral users

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 1dc9f2820fc179537b04ee243efdf72530ff8486..1dd5eae73b88e7c1ef6308435c0d1cf1c390ce29 100644
--- a/chrome/browser/resources/options/personal_options.js
+++ b/chrome/browser/resources/options/personal_options.js
@@ -123,6 +123,10 @@ cr.define('options', function() {
           // guest mode.
           $('enable-screen-lock').disabled = true;
           $('change-picture-button').disabled = true;

[Nikita (slow), 2012/03/07 10:03:04]

Same here, please enable back. We should not disable functionality. Users may
want to test all features of Chrome OS. 

Changing picture is one of them. Code in UserManager makes sure images wouldn't
be saved to LocalState/disk but they'll be in memory.

[use bartfab instead, 2012/03/07 11:10:08]

Done.

+        } else if (localStrings.getString('current_user_is_ephemeral') ==
+            'true') {
+          // Disable the change-picture-button for ephemeral users.
+          $('change-picture-button').disabled = true;
         }
       }