Revert 87415 - Convert more interfaces to the new thunk system. This goes up to and including

ppapi/proxy/ppb_file_ref_proxy.h

Index: ppapi/proxy/ppb_file_ref_proxy.h
===================================================================
--- ppapi/proxy/ppb_file_ref_proxy.h	(revision 87436)
+++ ppapi/proxy/ppb_file_ref_proxy.h	(working copy)
@@ -28,8 +28,9 @@
 
   static const Info* GetInfo();
 
-  static PP_Resource CreateProxyResource(PP_Resource file_system,
-                                         const char* path);
+  const PPB_FileRef_Dev* ppb_file_ref_target() const {
+    return static_cast<const PPB_FileRef_Dev*>(target_interface());
+  }
 
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);