Fix IllegalArgumentException in Privacy Guard Manager

On tablets such as manta a this occurs.  To reproduce go into PGM, press
the back button one time, then go back into PGM.

http://pastebin.com/N7XAybUB

Remove privacy guard fragment in onDestroyView

Change-Id: I61cebe273fa6fd514f18c86894acd176701148f6

Check if fragment transaction is empty before attempting to remove it

Change-Id: I08591c89559d33fee30ac2934fdbcc30637147da

PrivacyGuard fragment fix - change from empty check to isDestroyed check

Change-Id: I52fe44b7446cd16793df6ac9cdbe31e2ddd70210
Signed-off-by: Paul Beeler <sparksco@gmail.com>

PrivacyGuardManager: Reduce calls to getFragmentManager

Change-Id: I74f07a58b09cf0e9114d0c1c56e9a97d55ab0900