Allow custom font collection for DirectWrite font manager.

include/ports/SkTypeface_win.h

Index: include/ports/SkTypeface_win.h
diff --git a/include/ports/SkTypeface_win.h b/include/ports/SkTypeface_win.h
index b7373986c9396c88ca33a359c6e57588a2f5bbe1..da728ca3c0cfc635a4f79cd209ed13e2ae26115a 100644
--- a/include/ports/SkTypeface_win.h
+++ b/include/ports/SkTypeface_win.h
@@ -40,9 +40,11 @@ SK_API void SkTypeface_SetEnsureLOGFONTAccessibleProc(void (*)(const LOGFONT&));
 class SkFontMgr;
 class SkRemotableFontMgr;
 struct IDWriteFactory;
+struct IDWriteFontCollection;
 
 SK_API SkFontMgr* SkFontMgr_New_GDI();
-SK_API SkFontMgr* SkFontMgr_New_DirectWrite(IDWriteFactory* factory = NULL);
+SK_API SkFontMgr* SkFontMgr_New_DirectWrite(IDWriteFactory* factory = NULL,
+                                            IDWriteFontCollection* collection = NULL);
 
 /**
  *  Creates an SkFontMgr which renders using DirectWrite and obtains its data