Don't assume device has a status bar (TVs don't)

If this block of code doesn't find a StatusBar, it crashes the
ActivityThread, which restarts every couple of seconds right up
until the OS has had enough and decides to reboot.

Test: flashall && adb logcat | grep '.SystemUIService: java.lang.NullPointerException'
Bug: 62940302
Change-Id: Ib0adbadbc467df4941e03c7506762a7ec302d673