Update from https://crrev.com/316786

ui/gfx/transform_util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/transform_util.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
@@ skipping 480 matching lines @@
       perspective[0],
       perspective[1],
       perspective[2],
       perspective[3],
       quaternion[0],
       quaternion[1],
       quaternion[2],
       quaternion[3]);
 }
 
+float MatrixDistance(const Transform& a, const Transform& b) {
+  double sum = 0.0;
+
+  const SkMatrix44& a_data = a.matrix();
+  const SkMatrix44& b_data = b.matrix();
+
+  for (int row = 0; row < 4; ++row) {
+    for (int col = 0; col < 4; ++col) {
+      double diff = a_data.get(row, col) - b_data.get(row, col);
+      sum += diff * diff;
+    }
+  }
+
+  return static_cast<float>(std::sqrt(sum));
+}
+
+
 }  // namespace ui