Merge "Add developer option for back animation DO NOT MERGE" into tm-dev am: 064b49a1

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17619727



Change-Id: I15bc6d262232020d363f78d24a8b66dc07b1b658
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>