UsbDebuggingManager : Handle race condition when toggling rapidly

When toggling adb enable/disable rapidly, you can have the situation where the thread's
run() gets invoked but mAdbEnabled is already set to false, hence listenToSocket() never even
gets invoked in which case mOutputStream/mSocket are both null. This patchset adds checks
around that.

Change-Id: Iba56e7409435e22d690432fa663bc0a04a1a447d

Conflicts:
	services/java/com/android/server/usb/UsbDebuggingManager.java

(cherry picked from commit 898e628138678d2736b28e8d350819ad2194c005)
Fix navbar not showing when swiping down in expanded desktop with pie disable

Change-Id: Ia5f487ef26aeb1c67cf5f5e672332cc1c6fb1e6b
(cherry picked from commit ea0fd8d07cf9869dbb963957d25459d76fb199e1)