Start making all .cpp files compile-able on all platforms.

src/ports/SkFontMgr_win_dw_factory.cpp

Index: src/ports/SkFontMgr_win_dw_factory.cpp
diff --git a/src/ports/SkFontMgr_win_dw_factory.cpp b/src/ports/SkFontMgr_win_dw_factory.cpp
index 85ed56d695bd231008dc15fed3bb386b129b7b41..52e22aec52682ac6aefb82ebd3afe1f5437db24e 100644
--- a/src/ports/SkFontMgr_win_dw_factory.cpp
+++ b/src/ports/SkFontMgr_win_dw_factory.cpp
@@ -5,9 +5,14 @@
  * found in the LICENSE file.
  */
 
+#include "SkTypes.h"
+#if defined(SK_BUILD_FOR_WIN32)  // And !SKIA_GDI?
+
 #include "SkFontMgr.h"
 #include "SkTypeface_win.h"
 
 SkFontMgr* SkFontMgr::Factory() {
     return SkFontMgr_New_DirectWrite();
 }
+
+#endif//defined(SK_BUILD_FOR_WIN32)