Remove frame_display_index from TplDepFrame struct

Deprecate this variable.

BUG=aomedia:2728

Change-Id: I6feb926f6066bbf11ec7e6a738c9ce205e8e9f64
diff --git a/av1/encoder/encoder.h b/av1/encoder/encoder.h
index 82b3d3f..009fae0 100644
--- a/av1/encoder/encoder.h
+++ b/av1/encoder/encoder.h
@@ -199,7 +199,6 @@
   int height;
   int mi_rows;
   int mi_cols;
-  unsigned int frame_display_index;
   int base_rdmult;
 } TplDepFrame;
 
diff --git a/av1/encoder/tpl_model.c b/av1/encoder/tpl_model.c
index b50d531..669a14b 100644
--- a/av1/encoder/tpl_model.c
+++ b/av1/encoder/tpl_model.c
@@ -892,12 +892,9 @@
     if (frame_params.frame_type == KEY_FRAME || gop_eval) {
       tpl_data->tpl_frame[-i - 1].gf_picture = NULL;
       tpl_data->tpl_frame[-1 - 1].rec_picture = NULL;
-      tpl_data->tpl_frame[-i - 1].frame_display_index = 0;
     } else {
       tpl_data->tpl_frame[-i - 1].gf_picture = &cm->ref_frame_map[i]->buf;
       tpl_data->tpl_frame[-i - 1].rec_picture = &cm->ref_frame_map[i]->buf;
-      tpl_data->tpl_frame[-i - 1].frame_display_index =
-          cm->ref_frame_map[i]->display_order_hint;
     }
 
     ref_picture_map[i] = -i - 1;
@@ -928,11 +925,6 @@
 
     if (gf_index == cur_frame_idx) {
       tpl_frame->gf_picture = frame_input->source;
-      // frame display index = frame offset within the gf group + start frame of
-      // the gf group
-      tpl_frame->frame_display_index =
-          gf_group->frame_disp_idx[gf_index] +
-          cpi->common.current_frame.display_order_hint;
     } else {
       int frame_display_index = gf_index == gf_group->size
                                     ? cpi->rc.baseline_gf_interval
@@ -942,10 +934,6 @@
           cpi->compressor_stage);
       if (buf == NULL) break;
       tpl_frame->gf_picture = &buf->img;
-      // frame display index = frame offset within the gf group + start frame of
-      // the gf group
-      tpl_frame->frame_display_index =
-          frame_display_index + cpi->common.current_frame.display_order_hint;
     }
 
     if (frame_update_type != OVERLAY_UPDATE &&
@@ -1002,11 +990,6 @@
     tpl_frame->tpl_stats_ptr = tpl_data->tpl_stats_pool[process_frame_count];
     ++process_frame_count;
 
-    // frame display index = frame offset within the gf group + start frame of
-    // the gf group
-    tpl_frame->frame_display_index =
-        frame_display_index + cpi->common.current_frame.display_order_hint;
-
     gf_group->update_type[gf_index] = LF_UPDATE;
     gf_group->q_val[gf_index] = *pframe_qindex;