Merge "Merge "Set alpha to 0 on attach to avoid flicker at transition start."...

Merge "Merge "Set alpha to 0 on attach to avoid flicker at transition start." into udc-dev am: dc472531 am: bdb153f5" into udc-d1-dev-plus-aosp am: 31f87ed8 am: df78b368

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23252176



Change-Id: If981f221fa58c5b8310eab7eaa949729d5b648ac
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>