Convert single use EventTypes to class files.

xfa/fwl/core/cfwl_evtcheckstatechanged.cpp

Index: xfa/fwl/core/cfwl_evtcheckstatechanged.cpp
diff --git a/xfa/fwl/core/cfwl_evtcheckstatechanged.cpp b/xfa/fwl/core/cfwl_evtcheckstatechanged.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..53f7848fae939b8560b2b5ae589e8098565e6e6a
--- /dev/null
+++ b/xfa/fwl/core/cfwl_evtcheckstatechanged.cpp
@@ -0,0 +1,15 @@
+// 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
+
+#include "xfa/fwl/core/cfwl_evtcheckstatechanged.h"
+
+CFWL_EvtCheckStateChanged::CFWL_EvtCheckStateChanged() {}
+
+CFWL_EvtCheckStateChanged::~CFWL_EvtCheckStateChanged() {}
+
+CFWL_EventType CFWL_EvtCheckStateChanged::GetClassID() const {
+  return CFWL_EventType::CheckStateChanged;
+}