Merge "re-organize recents transition code for future changes" into udc-dev am: ca939575

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21497556



Change-Id: I1f827a60453e6e8a0a1e2d61efb0b32b24e7dae8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>