Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_msgsetfocus.cpp

Index: xfa/fwl/core/cfwl_msgsetfocus.cpp
diff --git a/xfa/fwl/core/cfwl_msgsetfocus.cpp b/xfa/fwl/core/cfwl_msgsetfocus.cpp
index 0463da1c6c6510cb815195ab4c2e944fb4e0c7ef..a4ce5519e18caaed19f2c51cf106a5e42af56f82 100644
--- a/xfa/fwl/core/cfwl_msgsetfocus.cpp
+++ b/xfa/fwl/core/cfwl_msgsetfocus.cpp
@@ -10,14 +10,11 @@
 
 #include "third_party/base/ptr_util.h"
 
-CFWL_MsgSetFocus::CFWL_MsgSetFocus() {}
+CFWL_MsgSetFocus::CFWL_MsgSetFocus()
+    : CFWL_Message(CFWL_MessageType::SetFocus) {}
 
 CFWL_MsgSetFocus::~CFWL_MsgSetFocus() {}
 
 std::unique_ptr<CFWL_Message> CFWL_MsgSetFocus::Clone() {
   return pdfium::MakeUnique<CFWL_MsgSetFocus>(*this);
 }
-
-CFWL_MessageType CFWL_MsgSetFocus::GetClassID() const {
-  return CFWL_MessageType::SetFocus;
-}