Fix crashes after notifying bad notification

If applications whose targetSDK is below N build notification
without contentView, contentView is created at inside of build()
function in Notification.Builder. If application apply
removeAllViews to this contentView, Notification View can have
id 'status_bar_latest_event_content' without standard layout of
notification. When inflating this notification, SystemUI try to wrap
it with NotificationTemplateViewWrapper(its id is
'status_bar_latest_event_content'), and crash, because it does not
have expected views.

Test: Install & launch attached apk in below BUG url to N devices,
and try to make notification by clicking 'do it' button.

https://code.google.com/p/android/issues/detail?id=223479

Bug:31948446
Change-Id: Ifcdc79a117613e8afd2e8ed098afd211cceabf88