gfx: Make conversions from Size to SizeF be explicit.

ui/gfx/geometry/size.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_GEOMETRY_SIZE_H_
 #define UI_GFX_GEOMETRY_SIZE_H_
 
 #include <iosfwd>
 #include <string>
 
 #include "base/compiler_specific.h"
-#include "ui/gfx/geometry/size_f.h"
 #include "ui/gfx/gfx_export.h"
 
 #if defined(OS_WIN)
 typedef struct tagSIZE SIZE;
 #elif defined(OS_MACOSX)
 typedef struct CGSize CGSize;
 #endif
 
 namespace gfx {
 
@@ skipping 32 matching lines @@
     set_height(height);
   }
 
   void Enlarge(int grow_width, int grow_height);
 
   void SetToMin(const Size& other);
   void SetToMax(const Size& other);
 
   bool IsEmpty() const { return !width() || !height(); }
 
-  operator SizeF() const {
-    return SizeF(static_cast<float>(width()), static_cast<float>(height()));
-  }
-
   std::string ToString() const;
 
  private:
   int width_;
   int height_;
 };
 
 inline bool operator==(const Size& lhs, const Size& rhs) {
   return lhs.width() == rhs.width() && lhs.height() == rhs.height();
 }
 
 inline bool operator!=(const Size& lhs, const Size& rhs) {
   return !(lhs == rhs);
 }
 
 // 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 Size& size, ::std::ostream* os);
 
+// Helper methods to scale a gfx::Size to a new gfx::Size.
+GFX_EXPORT Size ScaleToCeiledSize(const Size& size,
+                                  float x_scale,
+                                  float y_scale);
+GFX_EXPORT Size ScaleToCeiledSize(const Size& size, float x_scale);
+GFX_EXPORT Size ScaleToFlooredSize(const Size& size,
+                                   float x_scale,
+                                   float y_scale);
+GFX_EXPORT Size ScaleToFlooredSize(const Size& size, float x_scale);
+GFX_EXPORT Size ScaleToRoundedSize(const Size& size,
+                                   float x_scale,
+                                   float y_scale);
+GFX_EXPORT Size ScaleToRoundedSize(const Size& size, float x_scale);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_SIZE_H_