Base: Check ProcessesReady before broadcast

Most of the time testIsSystemReady is used to know if we are allowed to broadcast intents.
But in broadcast intent method we check mProcessesReady flag (not mSystemReady).
If we broadcast after systemReady flag but before ProcessesReady flag, system will crash

Adding condition to check if system & processes are ready fix that race condition
Signed-off-by: Fabien DUVOUX <fabien.duvoux@gmail.com>

Change-Id: I2eec1c4f280daf29f4741919a7636b02da341e32
Base: Add a shortcut in detecting if a window that contains the wallpaper is null or not

originally, a null window would be detected in WindowManagerService,
   an exception would be thrown, and then that would be caught in Session

Change-Id: I6681c81bafe8c1d8021959da7412fa308015b9dd