Merge "Add developer option for back animation DO NOT MERGE" into tm-dev am: 064b49a1 am: 3a6daba9 am: a92a047e

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



Change-Id: I33375bb408b1b4a4b2f108975141741cc511ec66
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>