Mojo: (POSIX) Pass channel handle to child.

mojo/system/platform_channel_handle.cc

Index: mojo/system/platform_channel_handle.cc
diff --git a/mojo/system/platform_channel_handle.cc b/mojo/system/platform_channel_handle.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f762c7a498ee8218403011f6e27810279d2fc553
--- /dev/null
+++ b/mojo/system/platform_channel_handle.cc
@@ -0,0 +1,37 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/system/platform_channel_handle.h"
+
+#include "build/build_config.h"
+#if defined(OS_POSIX)
+#include <unistd.h>
+#elif defined(OS_WIN)
+#include <windows.h>
+#else
+#error "Platform not yet supported."
+#endif
+
+#include "base/logging.h"
+
+namespace mojo {
+namespace system {
+
+void PlatformChannelHandle::CloseIfNecessary() {
+  if (!is_valid())
+    return;
+
+#if defined(OS_POSIX)
+  DPCHECK(close(fd) == 0);
+  fd = -1;
+#elif defined(OS_WIN)
+  DPCHECK(CloseHandle(handle));
+  handle = INVALID_HANDLE_VALUE;
+#else
+#error "Platform not yet supported."
+#endif
+}
+
+}  // namespace system
+}  // namespace mojo