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: Ie074945934d0319497ff1e237f8cec59b8531f53
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>