HeadsUp: Only remove heads up if attached to window

Attempting to remove mHeadsUpNoficiationView from the window manager
when it is not currently attached will throw an IllegalArgumentException
so we check if it is attached and if so remove it, otherwise carry on.

As well remove possible left children in statusbarview

Change-Id: Ida916eba496c4183e47288ef24a8a93c46a7eddf
SystemUI: improve one finger notification expansion

Sometimes the quick settings ribbon would eat the initial ACTION_DOWN
setting mInitialTouchY in the expand helper, but we are clearly not in a
notification that we can expand here. So only set the initial y point if
we are inside the notification scrollview.

Change-Id: I628553ac15cc6b4ee3c682fe46bd1d96c6bc154d
HeadsUp: Correctly add and remove the window

isAttachedToWindow() basically works to determine if the view was attached or not.

But on the boot up process when already addHeadsUpView is called but the system is not
fully up and a recreation happens (eg on TRDS...due that the UIModeManager is doing its work as soon as system is ready)
the view gets attached....but not removed on the recreation due that at this time isAttachedToWindow() will return false even though the
window was added.

To solve simply use a boolean instead of isAttachedToWindow()

Change-Id: Ib576a83cadc581683f2a5b0afc922c53b01888b7