An API to check if running in a demo user

Add an API to query if the calling app is running
in a demo user sandbox. This allows apps to customize
the starting experience to a potential customer.

Change-Id: I50e40f9a8c66da4b5672c1dc64606d7bedba3f8c
Fixes: 29833923
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index d128252..4e8676d 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -869,12 +869,25 @@
             }
         }
         synchronized (mUsersLock) {
-            UserInfo userInfo =  getUserInfoLU(userId);
+            UserInfo userInfo = getUserInfoLU(userId);
             return userInfo != null && userInfo.isManagedProfile();
         }
     }
 
     @Override
+    public boolean isDemoUser(int userId) {
+        int callingUserId = UserHandle.getCallingUserId();
+        if (callingUserId != userId && !hasManageUsersPermission()) {
+            throw new SecurityException("You need MANAGE_USERS permission to query if u=" + userId
+                    + " is a demo user");
+        }
+        synchronized (mUsersLock) {
+            UserInfo userInfo = getUserInfoLU(userId);
+            return userInfo != null && userInfo.isDemo();
+        }
+    }
+
+    @Override
     public boolean isRestricted() {
         synchronized (mUsersLock) {
             return getUserInfoLU(UserHandle.getCallingUserId()).isRestricted();