Added isUserNameSet

It can be used to check that the value returned by getUserName() was set
by the user and is not a default value returned by the system.

Test: UserManagerServiceUserInfoTest pass
Bug: 38138381
Change-Id: I0ca37970fda548508190bffd1fa7be95d4a15076
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index 63e2d47..30c4009 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -3069,6 +3069,14 @@
     }
 
     @Override
+    public boolean isUserNameSet(int userHandle) {
+        synchronized (mUsersLock) {
+            UserInfo userInfo = getUserInfoLU(userHandle);
+            return userInfo != null && userInfo.name != null;
+        }
+    }
+
+    @Override
     public int getUserHandle(int userSerialNumber) {
         synchronized (mUsersLock) {
             for (int userId : mUserIds) {