change flattenable factory to return sk_sp

tools/debugger/SkOverdrawMode.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorPriv.h"
 #include "SkOverdrawMode.h"
 #include "SkString.h"
@@ skipping 295 matching lines @@
 #endif
 
 private:
     friend class SkOverdrawMode;
 
     void flatten(SkWriteBuffer& buffer) const override { }
 
     typedef SkXfermode INHERITED;
 };
 
-SkFlattenable* SkOverdrawXfermode::CreateProc(SkReadBuffer& buffer) {
-    return Create();
+sk_sp<SkFlattenable> SkOverdrawXfermode::CreateProc(SkReadBuffer& buffer) {
+    return sk_sp<SkFlattenable>(Create());
 }
 
 sk_sp<SkXfermode> SkOverdrawMode::Make() { return sk_make_sp<SkOverdrawXfermode>(); }
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkOverdrawMode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkOverdrawXfermode)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END