Move xfa/fwl/core to xfa/fwl.

The core/ directory in FWL no-longer provides any context. This Cl moves all
of the core/ files up to the fwl/ folder.

As well, the CFWL_EvtFoo files are renamed CFWL_EventFoo and the CFWL_MsgFoo
files are renamed CFWL_MessageFoo. The event and message preceed the type in
order to keep the files sorted together and to make it clear that they're all
related.

Review-Url: https://codereview.chromium.org/2559173002
diff --git a/xfa/fwl/cfwl_eventtarget.h b/xfa/fwl/cfwl_eventtarget.h
new file mode 100644
index 0000000..1bca972
--- /dev/null
+++ b/xfa/fwl/cfwl_eventtarget.h
@@ -0,0 +1,35 @@
+// 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_CFWL_EVENTTARGET_H_
+#define XFA_FWL_CFWL_EVENTTARGET_H_
+
+#include <set>
+
+#include "core/fxcrt/fx_basic.h"
+#include "xfa/fwl/cfwl_event.h"
+
+class CFWL_Event;
+class CFWL_Widget;
+
+class CFWL_EventTarget {
+ public:
+  explicit CFWL_EventTarget(CFWL_Widget* pListener);
+  ~CFWL_EventTarget();
+
+  void SetEventSource(CFWL_Widget* pSource);
+  bool ProcessEvent(CFWL_Event* pEvent);
+
+  bool IsInvalid() const { return m_bInvalid; }
+  void FlagInvalid() { m_bInvalid = true; }
+
+ private:
+  std::set<CFWL_Widget*> m_widgets;
+  CFWL_Widget* m_pListener;
+  bool m_bInvalid;
+};
+
+#endif  // XFA_FWL_CFWL_EVENTTARGET_H_