Use the WebKit default fonts when specifying generic font families.

webkit/plugins/ppapi/webkit_forwarding_impl.h

Index: webkit/plugins/ppapi/webkit_forwarding_impl.h
===================================================================
--- webkit/plugins/ppapi/webkit_forwarding_impl.h	(revision 86427)
+++ webkit/plugins/ppapi/webkit_forwarding_impl.h	(working copy)
@@ -6,6 +6,10 @@
 
 #include "base/compiler_specific.h"
 
+namespace ppapi {
+struct Preferences;
+}
+
 namespace webkit {
 namespace ppapi {
 
@@ -17,6 +21,7 @@
   virtual void CreateFontForwarding(base::WaitableEvent* event,
                                     const PP_FontDescription_Dev& desc,
                                     const std::string& desc_face,
+                                    const ::ppapi::Preferences& prefs,
                                     Font** result) OVERRIDE;
 };