Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_msgkey.cpp

Index: xfa/fwl/core/cfwl_msgkey.cpp
diff --git a/xfa/fwl/core/cfwl_msgkey.cpp b/xfa/fwl/core/cfwl_msgkey.cpp
index 7d839f7203b1104bdf2e3da9a1ceeb2bd7a88287..a96220a6e6513d7e45852e5f0b18cf549aabcbd2 100644
--- a/xfa/fwl/core/cfwl_msgkey.cpp
+++ b/xfa/fwl/core/cfwl_msgkey.cpp
@@ -10,14 +10,10 @@
 
 #include "third_party/base/ptr_util.h"
 
-CFWL_MsgKey::CFWL_MsgKey() {}
+CFWL_MsgKey::CFWL_MsgKey() : CFWL_Message(CFWL_MessageType::Key) {}
 
 CFWL_MsgKey::~CFWL_MsgKey() {}
 
 std::unique_ptr<CFWL_Message> CFWL_MsgKey::Clone() {
   return pdfium::MakeUnique<CFWL_MsgKey>(*this);
 }
-
-CFWL_MessageType CFWL_MsgKey::GetClassID() const {
-  return CFWL_MessageType::Key;
-}