enforceCanSetDeviceOwnerLocked should enforce userId == USER_SYSTEM for non-split user mode

Bug: 27453111
Change-Id: I1acdfecdf4474696e904a6a4df189453be306aa4
diff --git a/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java b/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
index 212b37c..8c47087 100644
--- a/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
+++ b/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
@@ -969,6 +969,8 @@
 
         mContext.binder.callingUid = DpmMockContext.CALLER_SYSTEM_USER_UID;
 
+        when(mContext.userManagerForMock.isSplitSystemUser()).thenReturn(true);
+
         // Make sure the admin packge is installed to each user.
         setUpPackageManagerForAdmin(admin1, DpmMockContext.CALLER_SYSTEM_USER_UID);
         setUpPackageManagerForAdmin(admin3, DpmMockContext.CALLER_SYSTEM_USER_UID);
@@ -1008,6 +1010,7 @@
      * finds the right component from a package name upon migration.
      */
     public void testDeviceOwnerMigration() throws Exception {
+        when(mContext.userManagerForMock.isSplitSystemUser()).thenReturn(true);
         checkDeviceOwnerWithMultipleDeviceAdmins();
 
         // Overwrite the device owner setting and clears the clas name.