Don't show action bar when in camera preview.

There are 3 cases we need to toggle the action bar.
1. Touch in full screen mode. onToggleActionBarVisibility()
2. Swipe back and forth to film stripe from preview. onSwitchMode()
3. In full screen mode, current data becomes the preview.
onCurrentDataChanged()

bug:10563392
Change-Id: I576c49b767cd863da725cf991238c27440d85b9b
1 file changed