Merge "New hidden API to support the CTS test case that checks the file...

Merge "New hidden API to support the CTS test case that checks the file contents remains unaltered." into udc-dev am: 0fa26314 am: c032ef6c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22839500



Change-Id: I99ac72f6932609055a5f217ca920a2716b19f629
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>