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diff --git a/security/sandbox/chromium/base/file_descriptor_posix.h b/security/sandbox/chromium/base/file_descriptor_posix.h
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+++ b/security/sandbox/chromium/base/file_descriptor_posix.h
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+// Copyright (c) 2006-2009 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.
+
+#ifndef BASE_FILE_DESCRIPTOR_POSIX_H_
+#define BASE_FILE_DESCRIPTOR_POSIX_H_
+
+#include "base/files/file.h"
+#include "base/files/scoped_file.h"
+
+namespace base {
+
+constexpr int kInvalidFd = -1;
+
+// -----------------------------------------------------------------------------
+// We introduct a special structure for file descriptors in order that we are
+// able to use template specialisation to special-case their handling.
+//
+// IMPORTANT: This is primarily intended for use when sending file descriptors
+// over IPC. Even if |auto_close| is true, base::FileDescriptor does NOT close()
+// |fd| when going out of scope. Instead, a consumer of a base::FileDescriptor
+// must invoke close() on |fd| if |auto_close| is true.
+//
+// In the case of IPC, the the IPC subsystem knows to close() |fd| after sending
+// a message that contains a base::FileDescriptor if auto_close == true. On the
+// other end, the receiver must make sure to close() |fd| after it has finished
+// processing the IPC message. See the IPC::ParamTraits<> specialization in
+// ipc/ipc_message_utils.h for all the details.
+// -----------------------------------------------------------------------------
+struct FileDescriptor {
+  FileDescriptor() : fd(kInvalidFd), auto_close(false) {}
+
+  FileDescriptor(int ifd, bool iauto_close) : fd(ifd), auto_close(iauto_close) {
+  }
+
+  FileDescriptor(File file) : fd(file.TakePlatformFile()), auto_close(true) {}
+  explicit FileDescriptor(ScopedFD fd) : fd(fd.release()), auto_close(true) {}
+
+  bool operator==(const FileDescriptor& other) const {
+    return (fd == other.fd && auto_close == other.auto_close);
+  }
+
+  bool operator!=(const FileDescriptor& other) const {
+    return !operator==(other);
+  }
+
+  // A comparison operator so that we can use these as keys in a std::map.
+  bool operator<(const FileDescriptor& other) const {
+    return other.fd < fd;
+  }
+
+  int fd;
+  // If true, this file descriptor should be closed after it has been used. For
+  // example an IPC system might interpret this flag as indicating that the
+  // file descriptor it has been given should be closed after use.
+  bool auto_close;
+};
+
+}  // namespace base
+
+#endif  // BASE_FILE_DESCRIPTOR_POSIX_H_