Fold the FWL NoteThread classes up to the Thread classes.

xfa/fwl/core/ifwl_notethread.h

Index: xfa/fwl/core/ifwl_notethread.h
diff --git a/xfa/fwl/core/ifwl_notethread.h b/xfa/fwl/core/ifwl_notethread.h
deleted file mode 100644
index 30a29b5a9c330f150ae0d1224c510d8726e27ddc..0000000000000000000000000000000000000000
--- a/xfa/fwl/core/ifwl_notethread.h
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2016 PDFium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
-
-#ifndef XFA_FWL_CORE_IFWL_NOTETHREAD_H_
-#define XFA_FWL_CORE_IFWL_NOTETHREAD_H_
-
-#include "xfa/fwl/core/ifwl_thread.h"
-
-class IFWL_NoteDriver;
-
-class IFWL_NoteThread : public IFWL_Thread {
- public:
-  IFWL_NoteDriver* GetNoteDriver();
-};
-
-#endif  // XFA_FWL_CORE_IFWL_NOTETHREAD_H_