Merge "Only register stationary detector while idle" into sc-qpr1-dev am: 65f1d1a5 am: 1674a2d3 am: 33a2df97

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15639364

Change-Id: I8cf83e8ba1b5ef938c9a0440cc4bc6da024060a7