Create direct write font proxy classes and unit tests.

ui/gfx/win/direct_write.h

Index: ui/gfx/win/direct_write.h
diff --git a/ui/gfx/win/direct_write.h b/ui/gfx/win/direct_write.h
index f16e45c31410c09891f9f7b6e5359f9a8863c7b2..ec22a00634547c69801a38e1736d1ab0c26d6224 100644
--- a/ui/gfx/win/direct_write.h
+++ b/ui/gfx/win/direct_write.h
@@ -5,6 +5,8 @@
 #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 {
@@ -18,6 +20,9 @@ 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