Make a global enum to differentiate impl & proxy.

ppapi/shared_impl/ppb_file_ref_shared.h

Index: ppapi/shared_impl/ppb_file_ref_shared.h
diff --git a/ppapi/shared_impl/ppb_file_ref_shared.h b/ppapi/shared_impl/ppb_file_ref_shared.h
index 3d0a9f8af54145f083c6c2fc7a0caabf9aed41ed..2e7a20cc384bb49b5d76d51d6a6fd09a71e8167f 100644
--- a/ppapi/shared_impl/ppb_file_ref_shared.h
+++ b/ppapi/shared_impl/ppb_file_ref_shared.h
@@ -33,11 +33,8 @@ class PPAPI_SHARED_EXPORT PPB_FileRef_Shared
     : public Resource,
       public thunk::PPB_FileRef_API {
  public:
-  struct InitAsImpl {};
-  struct InitAsProxy {};
-
-  PPB_FileRef_Shared(const InitAsImpl&, const PPB_FileRef_CreateInfo& info);
-  PPB_FileRef_Shared(const InitAsProxy&, const PPB_FileRef_CreateInfo& info);
+  PPB_FileRef_Shared(ResourceObjectType type,
+                     const PPB_FileRef_CreateInfo& info);
   virtual ~PPB_FileRef_Shared();
 
   // Resource overrides.