Merge "KeyguardIndication: Allow no message as long as there's an icon" into sc-dev am: a5d01d30

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13585185

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I249971979b696935ba87c8e9c45896e1ed95a23b