add dummpy SkFontMgr::Factory() impl to font backends, so we can start testing it

trunk/src/ports/SkFontHost_win_dw.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTypes.h"
 #undef GetGlyphIndices
 
@@ skipping 1500 matching lines @@
                 getAdvanceData(fDWriteFontFace.get(),
                                glyphCount,
                                glyphIDs,
                                glyphIDsCount,
                                getWidthAdvance));
         }
     }
 
     return info;
 }
+
+///////////////////////////////////////////////////////////////////////////////
+
+#include "SkFontMgr.h"
+
+SkFontMgr* SkFontMgr::Factory() {
+    // todo
+    return NULL;
+}