Disable wallpaper button in Guest mode settings

ui/webui/resources/js/chromeos/ui_account_tweaks.js

Index: ui/webui/resources/js/chromeos/ui_account_tweaks.js
diff --git a/ui/webui/resources/js/chromeos/ui_account_tweaks.js b/ui/webui/resources/js/chromeos/ui_account_tweaks.js
index 76c2d90d1e93a7a158178ea97fc4135dec19351f..876942528b278e2c3d7e4e8d82cf399db3ad6c75 100644
--- a/ui/webui/resources/js/chromeos/ui_account_tweaks.js
+++ b/ui/webui/resources/js/chromeos/ui_account_tweaks.js
@@ -57,6 +57,28 @@ cr.define('uiAccountTweaks', function() {
   };
 
   /**
+   * Enables an element unless it should be disabled for the session type.
+   *
+   * @param {!Element} element Element that should be enabled.
+   */
+  UIAccountTweaks.enableElementIfPossible = function(element) {

[stevenjb, 2014/09/25 15:45:33]

Again, this function name seems too generic for the logic.

[michaelpg, 2014/09/29 18:50:56]

enableElementIfAllowed? enableElementIfEditable? tryToEnableElement?

enableElementForSessionType?

+    if (cr.isChromeOS) {

[stevenjb, 2014/09/25 15:45:33]

Shouldn't this always be true since this is in js/chromeos?

[michaelpg, 2014/09/29 18:50:56]

Yes. I've done a sanity check anyway, and nothing is calling this function
outside of chrome OS.

+      var sessionType;
+      if (UIAccountTweaks.loggedInAsGuest())
+        sessionType = SESSION_TYPE_GUEST;
+      else if (UIAccountTweaks.loggedInAsPublicAccount())
+        sessionType = SESSION_TYPE_PUBLIC;
+
+      if (sessionType &&
+          element.getAttribute(sessionType +'-visibility') == 'disabled') {
+        return;
+      }
+    }
+
+    element.disabled = false;
+  }
+
+  /**
    * Disables or hides some elements in specified type of session in ChromeOS.
    * All elements within given document with *sessionType*-visibility
    * attribute are either hidden (for *sessionType*-visibility="hidden")