Gallery2: fix the video playback after system language changed

- when system language changed, the activity would be destroyed
  and recreated. The subobject MoviePlayer would be also recreated.
  But in this case, MoviePlayer doesn't set some parameters like
  the URI, duration and etc. It cause the video playback failed.
- add the related function calls to restart the video playback.

Change-Id: I8dc011216bb5bcee8903ba3873ce37582927af45
CRs-Fixed: 597934