Update from https://crrev.com/316786

ui/gfx/transform_util.cc

Index: ui/gfx/transform_util.cc
diff --git a/ui/gfx/transform_util.cc b/ui/gfx/transform_util.cc
index 655ce57f2bb2b799cbf7da1b69164d97e5a42dd0..e96d96e6d9cf323a30b277c2f085549382208a46 100644
--- a/ui/gfx/transform_util.cc
+++ b/ui/gfx/transform_util.cc
@@ -498,4 +498,21 @@ std::string DecomposedTransform::ToString() const {
       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