Cherry-pick potential divide-by-zero fix

source/libvpx/vp9/common/vp9_prob.c

 /*
  *  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 11 matching lines @@
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 };
 
-
 static unsigned int tree_merge_probs_impl(unsigned int i,
                                           const vp9_tree_index *tree,
                                           const vp9_prob *pre_probs,
                                           const unsigned int *counts,
-                                          unsigned int count_sat,
-                                          unsigned int max_update,
                                           vp9_prob *probs) {
   const int l = tree[i];
   const unsigned int left_count = (l <= 0)
                  ? counts[-l]
-                 : tree_merge_probs_impl(l, tree, pre_probs, counts,
-                                         count_sat, max_update, probs);
+                 : tree_merge_probs_impl(l, tree, pre_probs, counts, probs);
   const int r = tree[i + 1];
   const unsigned int right_count = (r <= 0)
                  ? counts[-r]
-                 : tree_merge_probs_impl(r, tree, pre_probs, counts,
-                                         count_sat, max_update, probs);
+                 : tree_merge_probs_impl(r, tree, pre_probs, counts, probs);
   const unsigned int ct[2] = { left_count, right_count };
-  probs[i >> 1] = merge_probs(pre_probs[i >> 1], ct,
-                              count_sat, max_update);
+  probs[i >> 1] = mode_mv_merge_probs(pre_probs[i >> 1], ct);
   return left_count + right_count;
 }
 
 void vp9_tree_merge_probs(const vp9_tree_index *tree, const vp9_prob *pre_probs,
-                          const unsigned int *counts, unsigned int count_sat,
-                          unsigned int max_update_factor, vp9_prob *probs) {
-  tree_merge_probs_impl(0, tree, pre_probs, counts, count_sat,
-                        max_update_factor, probs);
+                          const unsigned int *counts, vp9_prob *probs) {
+  tree_merge_probs_impl(0, tree, pre_probs, counts, probs);
 }