Merge "Adding optional block to run before screenshot" into udc-dev am: a6550a83

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23356977



Change-Id: Id62b33726d2ad2e5796200373f64660c930875ce
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>