diff -r 000000000000 -r 6474c204b198 media/libvpx/vp9/encoder/vp9_treewriter.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/media/libvpx/vp9/encoder/vp9_treewriter.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,38 @@
+/*
+ *  Copyright (c) 2010 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.
+ */
+
+#include "vp9/encoder/vp9_treewriter.h"
+
+static void cost(int *costs, vp9_tree tree, const vp9_prob *probs,
+                 int i, int c) {
+  const vp9_prob prob = probs[i / 2];
+  int b;
+
+  for (b = 0; b <= 1; ++b) {
+    const int cc = c + vp9_cost_bit(prob, b);
+    const vp9_tree_index ii = tree[i + b];
+
+    if (ii <= 0)
+      costs[-ii] = cc;
+    else
+      cost(costs, tree, probs, ii, cc);
+  }
+}
+
+void vp9_cost_tokens(int *costs, const vp9_prob *probs, vp9_tree tree) {
+  cost(costs, tree, probs, 0, 0);
+}
+
+void vp9_cost_tokens_skip(int *costs, const vp9_prob *probs, vp9_tree tree) {
+  assert(tree[0] <= 0 && tree[1] > 0);
+
+  costs[-tree[0]] = vp9_cost_bit(probs[0], 0);
+  cost(costs, tree, probs, 2, 0);
+}