Fix MediaMetadataRetriever seek option OPTION_CLOSEST

When seeking with OPTION_CLOSEST, extractor returns the actual
closest target time via kKeyTargetTime, and read sample is the
sync frame before that. extractVideoFrame() needs to decode to
target time.

bug: 25783325
Change-Id: I94d6c196e2378b5efb608829b11aacf252d1fd46
1 file changed