Merge "Provide config for customize the showing strategy of back target." into...

Merge "Provide config for customize the showing strategy of back target." into udc-dev am: b11b27d4 am: dfcd99ea

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21578380



Change-Id: I601df0ed44f426ba76b896eea09e50519aff5af2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>