Added new (hidden) UserManager API to get all users, including pre-created ones.

Bug: 140750212
Test: manual verification

Change-Id: Iaef9db6216a7b18bf6f1f3e19f4a7428ec99f1da
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index ca273ba..8431fa3 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -663,12 +663,12 @@
         return null;
     }
 
-    @Override
     public @NonNull List<UserInfo> getUsers(boolean excludeDying) {
         return getUsers(/*excludePartial= */ true, excludeDying, /* excludePreCreated= */ true);
     }
 
-    private @NonNull List<UserInfo> getUsers(boolean excludePartial, boolean excludeDying,
+    @Override
+    public @NonNull List<UserInfo> getUsers(boolean excludePartial, boolean excludeDying,
             boolean excludePreCreated) {
         checkManageOrCreateUsersPermission("query users");
         synchronized (mUsersLock) {
@@ -2739,6 +2739,8 @@
         Preconditions.checkArgument(!UserInfo.isManagedProfile(flags),
                 "cannot pre-create managed profiles");
 
+        Slog.i(LOG_TAG, "Pre-creating user with flags " + UserInfo.flagsToString(flags));
+
         return createUserInternalUnchecked(/* name= */ null, flags,
                 /* parentId= */ UserHandle.USER_NULL, /* preCreate= */ true,
                 /* disallowedPackages= */ null);