mutliwindow: notify split view if layout changed [2/2]

Change-Id: I2bbdd58dcf89cd70aa01a4c2bfc06641508f632c
multiwindow: Fix NullPointerException

Change-Id: I5c423bcde7d191331be53ce180f827e7023dc472

Conflicts:
	services/java/com/android/server/am/ActivityManagerService.java
mutliwindow: notify split view if layout changed

Change-Id: I793b6d3dd05a5d1bbea178e646a1c6f14dec35c3

Conflicts:
	services/java/com/android/server/am/ActivityManagerService.java