libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_scale.h

 /*
  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 28 matching lines @@
 void vp9_setup_scale_factors_for_frame(struct scale_factors *sf,
                                        int other_w, int other_h,
                                        int this_w, int this_h);
 
 static INLINE int vp9_is_valid_scale(const struct scale_factors *sf) {
   return sf->x_scale_fp != REF_INVALID_SCALE &&
          sf->y_scale_fp != REF_INVALID_SCALE;
 }
 
 static INLINE int vp9_is_scaled(const struct scale_factors *sf) {
-  return sf->x_scale_fp != REF_NO_SCALE ||
-         sf->y_scale_fp != REF_NO_SCALE;
+  return vp9_is_valid_scale(sf) &&
+         (sf->x_scale_fp != REF_NO_SCALE || sf->y_scale_fp != REF_NO_SCALE);
+}
+
+static INLINE int valid_ref_frame_size(int ref_width, int ref_height,
+                                      int this_width, int this_height) {
+  return 2 * this_width >= ref_width &&
+         2 * this_height >= ref_height &&
+         this_width <= 16 * ref_width &&
+         this_height <= 16 * ref_height;
 }
 
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // VP9_COMMON_VP9_SCALE_H_