Split the common event classes out to files.

xfa/fwl/core/cfwl_evtmouse.h

Index: xfa/fwl/core/cfwl_evtmouse.h
diff --git a/xfa/fwl/core/cfwl_evtmouse.h b/xfa/fwl/core/cfwl_evtmouse.h
new file mode 100644
index 0000000000000000000000000000000000000000..386301ea5e60458a9e7244d57f159eb724951134
--- /dev/null
+++ b/xfa/fwl/core/cfwl_evtmouse.h
@@ -0,0 +1,25 @@
+// 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_CFWL_EVTMOUSE_H_
+#define XFA_FWL_CORE_CFWL_EVTMOUSE_H_
+
+#include "xfa/fwl/core/cfwl_event.h"
+
+class CFWL_EvtMouse : public CFWL_Event {
+ public:
+  CFWL_EvtMouse();
+  ~CFWL_EvtMouse() override;
+
+  CFWL_EventType GetClassID() const override;
+
+  FX_FLOAT m_fx;
+  FX_FLOAT m_fy;
+  uint32_t m_dwFlags;
+  FWL_MouseCommand m_dwCmd;
+};
+
+#endif  // XFA_FWL_CORE_CFWL_EVTMOUSE_H_