Cleanup: Get rid of OS_WIN/OS_POSIX ifdefs from MojoApplication

content/child/mojo/mojo_application.cc

Index: content/child/mojo/mojo_application.cc
diff --git a/content/child/mojo/mojo_application.cc b/content/child/mojo/mojo_application.cc
index bc1426ff3e139610098f0e2064f6da00ccc956a7..61ca8007e58f7e7ff34017ea8b5b9469a320e089 100644
--- a/content/child/mojo/mojo_application.cc
+++ b/content/child/mojo/mojo_application.cc
@@ -27,11 +27,7 @@ bool MojoApplication::OnMessageReceived(const IPC::Message& msg) {
 
 void MojoApplication::OnActivate(
     const IPC::PlatformFileForTransit& file) {
-#if defined(OS_POSIX)
-  base::PlatformFile handle = file.fd;
-#elif defined(OS_WIN)
-  base::PlatformFile handle = file;
-#endif
+  base::PlatformFile handle = IPC::PlatformFileForTransitToPlatformFile(file);
   mojo::ScopedMessagePipeHandle message_pipe =
       channel_init_.Init(handle,
                          ChildProcess::current()->io_message_loop_proxy());