[webkit-dev] Related to "WebKitSystemInterface.h"

Hello everyone, Just going through the WebKit source, I came across the header file: WebKitSystemInterface.h. That file is included by the Windows port of the Webkit. The other ports like wx and gtk are not including this header file at all. I am unsure about the use and purpose of this header file. I am new to the Webkit domain, so I do not have much idea about different files are their roles. Can anybody help me in this regard? I want to know about the role and need of this file as far as the porting Webkit to another platform is concerned. Thanks. Regards, Javed