Fix for loading progress for mapped files. am: 04f9f8718a am: cbc2313c17 am: 91cf7f2630

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/incremental_delivery/+/15790554

Change-Id: I8a698e899d308893f11af299c92958f2ef1f8242