VP9 SVC: Datarate test for dynamic bitrate change.
VP9 SVC: Datarate test for dynamic bitrate change.

Change-Id: Ie1cd990dcb19a4cc18de4a2e487791f399c4b3cb

webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx