Merge "Add documentation for LayoutParams.preferredRefreshRate" into tm-dev am: 336fcab7 am: b47c1c29

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17955874



Change-Id: I0a6516cf9b4e128ea70d536106817e42d2ecd969
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>