Revert of Make SharedMemoryHandle a class on Mac.

base/memory/shared_memory_handle.h

-// Copyright 2015 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_MEMORY_SHARED_MEMORY_HANDLE_H_
-#define BASE_MEMORY_SHARED_MEMORY_HANDLE_H_
-
-#include "build/build_config.h"
-
-#if defined(OS_WIN)
-#include <windows.h>
-#elif defined(OS_MACOSX) && !defined(OS_IOS)
-#include <sys/types.h>
-#include "base/base_export.h"
-#include "base/file_descriptor_posix.h"
-#include "base/macros.h"
-#elif defined(OS_POSIX)
-#include <sys/types.h>
-#include "base/file_descriptor_posix.h"
-#endif
-
-namespace base {
-
-class Pickle;
-
-// SharedMemoryHandle is a platform specific type which represents
-// the underlying OS handle to a shared memory segment.
-#if defined(OS_WIN)
-typedef HANDLE SharedMemoryHandle;
-#elif defined(OS_POSIX) && !(defined(OS_MACOSX) && !defined(OS_IOS))
-typedef FileDescriptor SharedMemoryHandle;
-#else
-class BASE_EXPORT SharedMemoryHandle {
- public:
-  enum Type {
-    // Indicates that the SharedMemoryHandle is backed by a POSIX fd.
-    POSIX,
-    // Indicates that the SharedMemoryHandle is backed by the Mach primitive
-    // "memory object".
-    MACH,
-  };
-
-  // The format that should be used to transmit |Type| over the wire.
-  typedef int TypeWireFormat;
-
-  // The default constructor returns an invalid SharedMemoryHandle.
-  SharedMemoryHandle();
-
-  // Constructs a SharedMemoryHandle backed by the components of a
-  // FileDescriptor. The newly created instance has the same ownership semantics
-  // as base::FileDescriptor. This typically means that the SharedMemoryHandle
-  // takes ownership of the |fd| if |auto_close| is true. Unfortunately, it's
-  // common for existing code to make shallow copies of SharedMemoryHandle, and
-  // the one that is finally passed into a base::SharedMemory is the one that
-  // "consumes" the fd.
-  explicit SharedMemoryHandle(const base::FileDescriptor& file_descriptor);
-  SharedMemoryHandle(int fd, bool auto_close);
-
-  // Standard copy constructor. The new instance shares the underlying OS
-  // primitives.
-  SharedMemoryHandle(const SharedMemoryHandle& handle);
-
-  // Standard assignment operator. The updated instance shares the underlying
-  // OS primitives.
-  SharedMemoryHandle& operator=(const SharedMemoryHandle& handle);
-
-  // Duplicates the underlying OS resources.
-  SharedMemoryHandle Duplicate() const;
-
-  // Comparison operators.
-  bool operator==(const SharedMemoryHandle& handle) const;
-  bool operator!=(const SharedMemoryHandle& handle) const;
-
-  // Returns the type.
-  Type GetType() const;
-
-  // Whether the underlying OS primitive is valid.
-  bool IsValid() const;
-
-  // Sets the POSIX fd backing the SharedMemoryHandle. Requires that the
-  // SharedMemoryHandle be backed by a POSIX fd.
-  void SetFileHandle(int fd, bool auto_close);
-
-  // This method assumes that the SharedMemoryHandle is backed by a POSIX fd.
-  // This is eventually no longer going to be true, so please avoid adding new
-  // uses of this method.
-  const FileDescriptor GetFileDescriptor() const;
-
- private:
-  Type type_;
-  FileDescriptor file_descriptor_;
-};
-#endif
-
-}  // namespace base
-
-#endif  // BASE_MEMORY_SHARED_MEMORY_HANDLE_H_