Update from https://crrev.com/320931

ui/gfx/transform.h

 // 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.
 
 #ifndef UI_GFX_TRANSFORM_H_
 #define UI_GFX_TRANSFORM_H_
 
 #include <iosfwd>
 #include <string>
 
@@ skipping 170 matching lines @@
   //    orthographic projection was added to the matrix sequence.
   //  - For z values, the new transform overrides any effect that the transform
   //    had on z, and instead it preserves the z value for any points that are
   //    transformed.
   //  - Because of linearity of transforms, this flattened transform also
   //    preserves the effect that any subsequent (multiplied from the right)
   //    transforms would have on z values.
   //
   void FlattenTo2d();
 
+  // Returns true if the 3rd row and 3rd column are both (0, 0, 1, 0).
+  bool IsFlat() const;
+
   // Returns the x and y translation components of the matrix.
   Vector2dF To2dTranslation() const;
 
   // Applies the transformation to the point.
   void TransformPoint(Point3F* point) const;
 
   // Applies the transformation to the point.
   void TransformPoint(Point* point) const;
 
   // Applies the reverse transformation on the point. Returns true if the
@@ skipping 69 matching lines @@
 };
 
 // This is declared here for use in gtest-based unit tests but is defined in
 // the gfx_test_support target. Depend on that to use this in your unit test.
 // This should not be used in production code - call ToString() instead.
 void PrintTo(const Transform& transform, ::std::ostream* os);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_TRANSFORM_H_