Merge "media: document MediaFormat.KEY_FRAME_RATE better" into nyc-dev am: 017567ae1d am: 7d7f8f2724
am: 251a6dbb82

* commit '251a6dbb82cf5a6855f94c2c8b0a742ef477eaa9':
  media: document MediaFormat.KEY_FRAME_RATE better

Change-Id: I9a279f91e74241b62d45ac4f0bb6fa037276998d