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: a0cbcf65

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



Change-Id: I4864b00823f63c3f02dd06d2ff4f8880c33b19e8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>