Force all font backends to override onGetFontDescriptor, so we can

include/core/SkFontHost.h

Index: include/core/SkFontHost.h
===================================================================
--- include/core/SkFontHost.h	(revision 8346)
+++ include/core/SkFontHost.h	(working copy)
@@ -152,23 +152,6 @@
 
     ///////////////////////////////////////////////////////////////////////////
 
-    /** Write a unique identifier to the stream, so that the same typeface can
-        be retrieved with Deserialize(). The standard format is to serialize
-        a SkFontDescriptor followed by a uint32_t length value. If the length
-        is non-zero then the following bytes (of that length) represent a
-        serialized copy of the font which can be recreated from a stream.
-    */
-    static void Serialize(const SkTypeface*, SkWStream*);
-
-    /** Given a stream created by Serialize(), return a new typeface (like
-        CreateTypeface) which is either an exact match to the one serialized
-        or the best available typeface based on the data in the deserialized
-        SkFontDescriptor.
-     */
-    static SkTypeface* Deserialize(SkStream*);
-
-    ///////////////////////////////////////////////////////////////////////////
-
     friend class SkTypeface;
 };