Update from https://crrev.com/320931

ui/gfx/transform.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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/gfx/transform.h"
 
 #include <cmath>
@@ skipping 376 matching lines @@
 void Transform::FlattenTo2d() {
   matrix_.set(2, 0, 0.0);
   matrix_.set(2, 1, 0.0);
   matrix_.set(0, 2, 0.0);
   matrix_.set(1, 2, 0.0);
   matrix_.set(2, 2, 1.0);
   matrix_.set(3, 2, 0.0);
   matrix_.set(2, 3, 0.0);
 }
 
+bool Transform::IsFlat() const {
+  return matrix_.get(2, 0) == 0.0 && matrix_.get(2, 1) == 0.0 &&
+         matrix_.get(0, 2) == 0.0 && matrix_.get(1, 2) == 0.0 &&
+         matrix_.get(2, 2) == 1.0 && matrix_.get(3, 2) == 0.0 &&
+         matrix_.get(2, 3) == 0.0;
+}
+
 Vector2dF Transform::To2dTranslation() const {
   return gfx::Vector2dF(SkMScalarToFloat(matrix_.get(0, 3)),
                         SkMScalarToFloat(matrix_.get(1, 3)));
 }
 
 void Transform::TransformPoint(Point* point) const {
   DCHECK(point);
   TransformPointInternal(matrix_, point);
 }
 
@@ skipping 147 matching lines @@
       matrix_.get(2, 1),
       matrix_.get(2, 2),
       matrix_.get(2, 3),
       matrix_.get(3, 0),
       matrix_.get(3, 1),
       matrix_.get(3, 2),
       matrix_.get(3, 3));
 }
 
 }  // namespace gfx