Correct normal computation for inverted polygons.

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 180 matching lines @@
 
   // 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 transformation to the vector.
+  void TransformVector(Vector3dF* vector) const;
+
   // Applies the reverse transformation on the point. Returns true if the
   // transformation can be inverted.
   bool TransformPointReverse(Point3F* point) const;
 
   // Applies the reverse transformation on the point. Returns true if the
   // transformation can be inverted. Rounds the result to the nearest point.
   bool TransformPointReverse(Point* point) const;
 
   // Applies transformation on the given rect. After the function completes,
   // |rect| will be the smallest axis aligned bounding rect containing the
@@ skipping 48 matching lines @@
 
   std::string ToString() const;
 
  private:
   void TransformPointInternal(const SkMatrix44& xform,
                               Point* point) const;
 
   void TransformPointInternal(const SkMatrix44& xform,
                               Point3F* point) const;
 
+  void TransformVectorInternal(const SkMatrix44& xform,
+                               Vector3dF* vector) const;
+
   SkMatrix44 matrix_;
 
   // copy/assign are allowed.
 };
 
 // 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_