Gallery2: Recycle effect instance when MovieActivity pauses

VideoView will deallocate audio track for local video playback when
MovieActivity being paused, which causes audio effect being released
twice when onDestroy() is called.

To avoid such special case, we should ensure effect be
deallocated/allocated when video view call pause/resume.

Change-Id: I571f9f3126be747ebe4e65a01f6880941d00d25d
CRs-Fixed: 522349, 523853, 524557
Gallery2: fix save button is disabled after rotate in TrimVideo

After rotating the phone, TrimVideo activity will recreate,
the save button will be disabled when create activity.

We restore the state of the save button.

CRs-Fixed: 521010

Change-Id: Ided934a6e54b20289c21608f2df19875d25adb7d