Refactor get_prediction_decay_rate()
Refactor get_prediction_decay_rate()

Replace cpi by frame_info
Rename next_frame by frame_stats

Change-Id: I909f01ce724aac13030931970fba8b7b3f4d0080

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