MoviePlayer: don't pause after leaving for a long time

Currently, after leaving video player for more than 3 minutes,
the video will be paused upon returning. Remove this behavior as it's
not required for non-streaming videos.

Change-Id: Ibe58bcc35bb3c3c95198447978d180fbd54e7b12
MoviePlayer: don't resume playing if there is pending dialog

In onResume(), mDelayVideoRunnable should be posted after dialog check.

Change-Id: I3b7789090acb1a49803a66766883414768b59ac7