Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_msgkillfocus.cpp

Index: xfa/fwl/core/cfwl_msgkillfocus.cpp
diff --git a/xfa/fwl/core/cfwl_msgkillfocus.cpp b/xfa/fwl/core/cfwl_msgkillfocus.cpp
index 0c8ac470299d19b29379a76229fcabe0716a681a..32d0cc41cbd16ece5704c4380a7b8d9bbcbdaf5d 100644
--- a/xfa/fwl/core/cfwl_msgkillfocus.cpp
+++ b/xfa/fwl/core/cfwl_msgkillfocus.cpp
@@ -10,14 +10,11 @@
 
 #include "third_party/base/ptr_util.h"
 
-CFWL_MsgKillFocus::CFWL_MsgKillFocus() {}
+CFWL_MsgKillFocus::CFWL_MsgKillFocus()
+    : CFWL_Message(CFWL_MessageType::KillFocus) {}
 
 CFWL_MsgKillFocus::~CFWL_MsgKillFocus() {}
 
 std::unique_ptr<CFWL_Message> CFWL_MsgKillFocus::Clone() {
   return pdfium::MakeUnique<CFWL_MsgKillFocus>(*this);
 }
-
-CFWL_MessageType CFWL_MsgKillFocus::GetClassID() const {
-  return CFWL_MessageType::KillFocus;
-}