Fix MediaTimeProvider seek & time drift recovery issue

Handle MEDIA_SKIPPED event

Prevent notifyTimedEvent events (REFRESH_AND_/NOTIFY_TIME)
to eclipse NOTIFY_SEEK events.

Add automatic seek when time drifts too much.  This should
not happen under normal circumstances, but is there to recover
from any unannounced media time discontinuity.

Change-Id: I8d7fdac2b0b6a9e62d2860461e6a25788e77fef8
Signed-off-by: Lajos Molnar <lajos@google.com>
Bug: 10954008