Create direct write font proxy classes and unit tests.

ui/gfx/win/direct_write.h

 // Copyright 2014 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_WIN_DIRECT_WRITE_H_
 #define UI_GFX_WIN_DIRECT_WRITE_H_
 
+#include <dwrite.h>
+
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 namespace win {
 
 // Returns whether DirectWrite font rendering should be used.
 GFX_EXPORT bool ShouldUseDirectWrite();
 
 GFX_EXPORT void MaybeInitializeDirectWrite();
 
 // Returns true if we are using DirectWrite for font metrics and rendering.
 GFX_EXPORT bool IsDirectWriteEnabled();
 
+// Creates a DirectWrite factory, if using DirectWrite.
+GFX_EXPORT void CreateDWriteFactory(IDWriteFactory** factory);
+
 }  // namespace win
 }  // namespace gfx
 
 #endif  // UI_GFX_WIN_DIRECT_WRITE_H_