Adds assignment operator like function to Transform.

ui/gfx/transform.h

 // Copyright (c) 2011 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_
 #pragma once
 
 namespace gfx {
 class Point;
@@ skipping 56 matching lines @@
   // transformed successfully.
   virtual bool TransformPoint(gfx::Point* point) = 0;
 
   // Applies the reverse transformation on the point. Returns true if the point
   // is transformed successfully.
   virtual bool TransformPointReverse(gfx::Point* point) = 0;
 
   // Applies transformation on the rectangle. Returns true of the rectangle is
   // transformed successfully.
   virtual bool TransformRect(gfx::Rect* rect) = 0;
+
+  // operator=.
+  virtual void Copy(const Transform& transform) = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_GFX_TRANSFORM_H_