base

Bring consistency to FLAG_ONLY_ALERT_ONCE semantics.

For updates, the sounds layer checks for existence of the flag on the
new version while the heads up was checking for the flag on the
old version.

Both now agree to check the new version.

Bug: 14255617
Change-Id: Ib617df11f0dea17b5dfdf2ef6330bdbd18032ac6