Make PlatformFileForTransit its own class on Windows.

components/nacl/renderer/ppb_nacl_private_impl.cc

Index: components/nacl/renderer/ppb_nacl_private_impl.cc
diff --git a/components/nacl/renderer/ppb_nacl_private_impl.cc b/components/nacl/renderer/ppb_nacl_private_impl.cc
index 0d50484f8d8be726f6b96fc23a64dd162ad3d628..8d8faeb54d13ba79bb9a4bb2981d177cad6feafc 100644
--- a/components/nacl/renderer/ppb_nacl_private_impl.cc
+++ b/components/nacl/renderer/ppb_nacl_private_impl.cc
@@ -461,8 +461,7 @@ void PPBNaClPrivate::LaunchSelLdr(
   if (nexe_file_info->handle != PP_kInvalidFileHandle)
     nexe_for_transit = base::FileDescriptor(nexe_file_info->handle, true);
 #elif defined(OS_WIN)
-  nexe_for_transit = IPC::PlatformFileForTransit(nexe_file_info->handle,

[Mark Seaborn, 2017/04/28 22:45:21]

You said "This CL includes a small fix to ppb_nacl_private_impl.cc, which
previously leaked a HANDLE on Windows, but not on an fd on POSIX".

In what case was it leaking a HANDLE (on error or success or both)?  Are you
saying that this is fixed by the change?

[erikchen, 2017/04/28 23:24:37]

Both and yes. I've substantially expanded the CL description with details.

-                                                 base::GetCurrentProcId());
+  nexe_for_transit = IPC::PlatformFileForTransit(nexe_file_info->handle);
 #else
 # error Unsupported target platform.
 #endif