CMS 10 - HttpContext.Current is null when saving approval sequence

Description

Steps to reproduce
1. Create a custom SecurityEntityProvider that calls the HttpContext.Current in the Search method.
2. In the edit page, click Edit Approval Sequence.
3. Enable an approval sequence and enter the reviewer's role.
4. Save the approval sequence.

Expected: You can save successfully.
Actual: NullReferenceException in the custom SecurityEntityProvider created in step 1.