Use notification heights on layouts internal to the notificaitons.
Use row heights where padding needs to be protected, on row layout decisions.
Clean up values-xhdpi/dimens.xml since there is no longer a values-hdpi/dimens.xml.
Bug: 6475098
Bug: 6489095
Change-Id: I44750574c6e23336585a432a38c5f1ba183b6cbc