Merge mr_pick_inter_mode and pick_inter_mode

Merged multi-resolution motion estimation with regular motion
estimation function in order to remove duplicated part. This
caused slight changes in multi-resulotion encoder quality &
performance.

Change-Id: Ib4ecc7acfebfe5eea959b5b91febae6db7b95fd1

vp8/encoder/encodeframe.c

@@ -1186,23 +1186,8 @@ int vp8cx_encode_inter_macroblock
     }
     else
     {
-#if CONFIG_MULTI_RES_ENCODING
-        if (cpi->oxcf.mr_encoder_id == 0)
-        {
-            /* Lowest-resolution encoding */
-            vp8_pick_inter_mode(cpi, x, recon_yoffset, recon_uvoffset, &rate,
-                                    &distortion, &intra_error);
-
-        }else
-        {
-            /* Higher-resolution encoding */
-            vp8_mr_pick_inter_mode(cpi, x, recon_yoffset, recon_uvoffset, &rate,
-                                &distortion, &intra_error, mb_row, mb_col);
-        }
-#else
         vp8_pick_inter_mode(cpi, x, recon_yoffset, recon_uvoffset, &rate,
-                            &distortion, &intra_error);
-#endif
+                            &distortion, &intra_error, mb_row, mb_col);
     }
 
     cpi->prediction_error += distortion;

vp8/encoder/pickinter.h

@@ -16,14 +16,8 @@
 
 extern void vp8_pick_inter_mode(VP8_COMP *cpi, MACROBLOCK *x, int recon_yoffset,
                                 int recon_uvoffset, int *returnrate,
-                                int *returndistortion, int *returnintra);
+                                int *returndistortion, int *returnintra,
+                                int mb_row, int mb_col);
 extern void vp8_pick_intra_mode(VP8_COMP *cpi, MACROBLOCK *x, int *rate);
 
-#if CONFIG_MULTI_RES_ENCODING
-extern void vp8_mr_pick_inter_mode(VP8_COMP *cpi, MACROBLOCK *x,
-                                   int recon_yoffset, int recon_uvoffset,
-                                   int *returnrate, int *returndistortion,
-                                   int *returnintra, int mb_row, int mb_col);
-#endif
-
 #endif

vp8/vp8_cx_iface.c

@@ -361,6 +361,10 @@ static vpx_codec_err_t set_vp8e_config(VP8_CONFIG *oxcf,
     }
 
 #if CONFIG_MULTI_RES_ENCODING
+    /* When mr_cfg is NULL, oxcf->mr_total_resolutions and oxcf->mr_encoder_id
+     * are both memset to 0, which ensures the correct logic under this
+     * situation.
+     */
     if(mr_cfg)
     {
         oxcf->mr_total_resolutions        = mr_cfg->mr_total_resolutions;