NuPlayerDriver: fix current position for stop and pause.

When start() is called after EOS, it means restarting from the beginning of the stream.
Fix racing conditon on accessing some members.
Report seekTo position before any notifyPosition is called.

Bug: 17031731
Bug: 17178928
Change-Id: I008b827288cf28d39e2a943373fe1e5d7d6c2595
2 files changed