Merge "Optimize activity snapshot for shell transition." into udc-qpr-dev am: 5f494802

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23898517



Change-Id: I94406db33932b8afecaa021d17eefa07a56e1129
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>