Remove the use of use_lastframe_partitioning at speed 4

The use of use_lastframe_partitioning is totally removed in good-
quality encoding. Its usage in real-time encoding needs to be
evaluated to see if it can be removed too.

The Borg tests at speed 4 showed:
stdhd set: 0.220% psnr gain, 0.166% ssim gain;
derf set:  0.329% psnr gain, 0.476% ssim gain.

Speed test on selected clips showed 1.54% speedup.(Worst case:
pedestrian_area_1080p25.y4m, speed loss: 1.5%)

Change-Id: I1c844d329b0b5678558439b887297c1be7ddab00

vp9/encoder/vp9_encodeframe.c

@@ -2466,6 +2466,9 @@ static void encode_rd_sb_row(VP9_COMP *cpi, const TileInfo *const tile,
     vp9_zero(cpi->mb.pred_mv);
     cpi->pc_root->index = 0;
 
+    // TODO(yunqingwang): use_lastframe_partitioning is no longer used in good-
+    // quality encoding. Need to evaluate it in real-time encoding later to
+    // decide if it can be removed too. And then, do the code cleanup.
     if ((sf->partition_search_type == SEARCH_PARTITION &&
          sf->use_lastframe_partitioning) ||
          sf->partition_search_type == FIXED_PARTITION ||

vp9/encoder/vp9_speed_features.c

@@ -104,15 +104,11 @@ static void set_good_speed_feature(VP9_COMP *cpi, VP9_COMMON *cm,
                                                       : USE_LARGESTALL;
 
     if (MIN(cm->width, cm->height) >= 720) {
-      sf->lf_motion_threshold = LOW_MOTION_THRESHOLD;
-      sf->last_partitioning_redo_frequency = 3;
       sf->disable_split_mask = cm->show_frame ? DISABLE_ALL_SPLIT
                                               : DISABLE_ALL_INTER_SPLIT;
       sf->adaptive_pred_interp_filter = 0;
     } else {
       sf->disable_split_mask = LAST_AND_INTRA_SPLIT_ONLY;
-      sf->last_partitioning_redo_frequency = 2;
-      sf->lf_motion_threshold = NO_MOTION_THRESHOLD;
     }
 
     sf->reference_masking = 1;
@@ -123,7 +119,6 @@ static void set_good_speed_feature(VP9_COMP *cpi, VP9_COMMON *cm,
     sf->disable_filter_search_var_thresh = 100;
     sf->comp_inter_joint_search_thresh = BLOCK_SIZES;
     sf->auto_min_max_partition_size = CONSTRAIN_NEIGHBORING_MIN_MAX;
-    sf->adjust_partitioning_from_last_frame = 1;
 
     if (MIN(cm->width, cm->height) >= 720)
       sf->partition_search_breakout_dist_thr = (1 << 24);
@@ -147,8 +142,6 @@ static void set_good_speed_feature(VP9_COMP *cpi, VP9_COMMON *cm,
     sf->cb_pred_filter_search = 1;
     sf->alt_ref_search_fp = 1;
     sf->motion_field_mode_search = !boosted;
-    sf->lf_motion_threshold = LOW_MOTION_THRESHOLD;
-    sf->last_partitioning_redo_frequency = 2;
     sf->recode_loop = ALLOW_RECODE_KFMAXBW;
     sf->adaptive_rd_thresh = 3;
     sf->mode_skip_start = 6;
@@ -171,7 +164,6 @@ static void set_good_speed_feature(VP9_COMP *cpi, VP9_COMMON *cm,
     sf->mode_search_skip_flags |= FLAG_SKIP_COMP_REFMISMATCH |
                                   FLAG_EARLY_TERMINATE;
     sf->disable_filter_search_var_thresh = 200;
-    sf->use_lastframe_partitioning = LAST_FRAME_PARTITION_ALL;
     sf->use_lp32x32fdct = 1;
     sf->use_fast_coef_updates = ONE_LOOP_REDUCED;
     sf->use_fast_coef_costing = 1;