Merge "Load back-gesture model on background thread." into tm-qpr-dev am: fddc399c am: 30e2cea7

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19440790



Change-Id: Ib493c694a68f50d1ae0d5bc31149db0f81ad47cc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>