WindowManagerService: Fix application transitions in immersive mode.

Change-Id: If7d3fc3ab566dedc3a5b38cd0a6dc3185f494e20
Signed-off-by: Carlo Savignano <stevewatersy@gmail.com>
Fix hot reboot in powermenu

Fixes AOSPA-557
Accessing showGlobalActionsDialog() from different threads
(one for broadcasts and one for the actual longpress power button action)
caused a hot reboot when accessing the power menu from quick settings and then from power button.

Change-Id: I4b6efd192404f073c0d1b5655152ae736a398cbd
Not needed I believe