More precise argument name in isGuestUser

The 'int id' refers to a userId.

Test: treehugger
Change-Id: I9f5aad8acdc82e078227c5b39ffb108084531dec

core/java/android/os/UserManager.java

@@ -1529,8 +1529,8 @@ public class UserManager {
      * @hide
      */
     @UnsupportedAppUsage
-    public boolean isGuestUser(int id) {
-        UserInfo user = getUserInfo(id);
+    public boolean isGuestUser(@UserIdInt int userId) {
+        UserInfo user = getUserInfo(userId);
         return user != null && user.isGuest();
     }