Merge \"media: document VP9 CSD for MediaCodec\" into nyc-dev

 Codec-specific data in the format is automatically submitted to the codec upon {@link #start};

 you <strong>MUST NOT</strong> submit this data explicitly. If the format did not contain codec

 specific data, you can choose to submit it using the specified number of buffers in the correct

 order, according to the format requirements. Alternately, you can concatenate all codec-specific

 data and submit it as a single codec-config buffer.

 order, according to the format requirements. In case of H.264 AVC, you can also concatenate all

 codec-specific data and submit it as a single codec-config buffer.

 <p>

 Android uses the following codec-specific data buffers. These are also required to be set in

 the track format for proper {@link MediaMuxer} track configuration. Each parameter set and the

    <td class=NA>Not Used</td>

    <td class=NA>Not Used</td>

   </tr>

   <tr>

    <td>VP9</td>

    <td>VP9 <a href="http://wiki.webmproject.org/vp9-codecprivate">CodecPrivate</a> Data

        (optional)</td>

    <td class=NA>Not Used</td>

    <td class=NA>Not Used</td>

   </tr>

  </tbody>

 </table>