Check mStatusBarWindowHidden bit when deciding to hide status bar

Ensures that we unhide status bar icons when (for instance), showing the
status bar in the camera from the keyguard

Change-Id: Ica1b622dd9e0a913575664b98825bc67809e5e72
Fixes: 79511463
Bug: 79700037 (possibly related)
Test: launch camera from keyguard, swipe status bar down, see icons