Gallery2: Fix show the wrong UI after resume when the video stop.

The view background is transparent when the video stop,
and then it will show the wallpaper after resume.

set transparent background when the video is playing or pause,
and set black background on other status(stop,end,error)

Change-Id: Ib97ed6b4f716ff512e7f6f258fd8ddfbdecf5587
CRs-Fixed: 952289