Merge "Add an extra transition type in TransitSession for custom transition."...

Merge "Add an extra transition type in TransitSession for custom transition." into udc-dev am: e4c4d532

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22802760



Change-Id: I27964281be3cdb15137b7f709960acf9d15634d3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>