b/12068020 add nonce to InputDeviceDescriptor. Do not merge

This is a cherry-pick of https://googleplex-android-review.git.corp.google.com/#/c/401795/

Adds a nonce field to allow generation of unique descriptors for
input devices.

Change-Id: Ie82bfb728bea95792b3b138dd3974f8b0aff63e0
1 file changed