libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_scale.c

Index: source/libvpx/vp9/common/vp9_scale.c
===================================================================
--- source/libvpx/vp9/common/vp9_scale.c	(revision 281795)
+++ source/libvpx/vp9/common/vp9_scale.c	(working copy)
@@ -33,14 +33,6 @@
   return (other_size << REF_SCALE_SHIFT) / this_size;
 }
 
-static int check_scale_factors(int other_w, int other_h,
-                               int this_w, int this_h) {
-  return 2 * this_w >= other_w &&
-         2 * this_h >= other_h &&
-         this_w <= 16 * other_w &&
-         this_h <= 16 * other_h;
-}
-
 MV32 vp9_scale_mv(const MV *mv, int x, int y, const struct scale_factors *sf) {
   const int x_off_q4 = scaled_x(x << SUBPEL_BITS, sf) & SUBPEL_MASK;
   const int y_off_q4 = scaled_y(y << SUBPEL_BITS, sf) & SUBPEL_MASK;
@@ -54,7 +46,7 @@
 void vp9_setup_scale_factors_for_frame(struct scale_factors *sf,
                                        int other_w, int other_h,
                                        int this_w, int this_h) {
-  if (!check_scale_factors(other_w, other_h, this_w, this_h)) {
+  if (!valid_ref_frame_size(other_w, other_h, this_w, this_h)) {
     sf->x_scale_fp = REF_INVALID_SCALE;
     sf->y_scale_fp = REF_INVALID_SCALE;
     return;