Revert of Revert of Make SharedMemoryHandle a class on Mac.

base/memory/shared_memory.h

 // Copyright (c) 2012 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_H_
 #define BASE_MEMORY_SHARED_MEMORY_H_
 
 #include "build/build_config.h"
 
 #include <string>
 
 #if defined(OS_POSIX)
 #include <stdio.h>
 #include <sys/types.h>
 #include <semaphore.h>
 #endif
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
+#include "base/memory/shared_memory_handle.h"
 #include "base/process/process_handle.h"
 
 #if defined(OS_POSIX)
 #include "base/file_descriptor_posix.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
 #endif
 
 namespace base {
 
 class FilePath;
 
-// 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)
-typedef FileDescriptor SharedMemoryHandle;
-#endif
-
 // Options for creating a shared memory object.
 struct SharedMemoryCreateOptions {
   SharedMemoryCreateOptions()
       : name_deprecated(NULL),
         size(0),
         open_existing_deprecated(false),
         executable(false),
         share_read_only(false) {}
 
   // DEPRECATED (crbug.com/345734):
@@ skipping 32 matching lines @@
   explicit SharedMemory(const std::wstring& name);
 #endif
 
   // Create a new SharedMemory object from an existing, open
   // shared memory file.
   //
   // WARNING: This does not reduce the OS-level permissions on the handle; it
   // only affects how the SharedMemory will be mmapped.  Use
   // ShareReadOnlyToProcess to drop permissions.  TODO(jln,jyasskin): DCHECK
   // that |read_only| matches the permissions of the handle.
-  SharedMemory(SharedMemoryHandle handle, bool read_only);
+  SharedMemory(const SharedMemoryHandle& handle, bool read_only);
 
   // Create a new SharedMemory object from an existing, open
   // shared memory file that was created by a remote process and not shared
   // to the current process.
-  SharedMemory(SharedMemoryHandle handle, bool read_only,
+  SharedMemory(const SharedMemoryHandle& handle,
+               bool read_only,
                ProcessHandle process);
 
   // Closes any open files.
   ~SharedMemory();
 
   // Return true iff the given handle is valid (i.e. not the distingished
   // invalid value; NULL for a HANDLE and -1 for a file descriptor)
   static bool IsHandleValid(const SharedMemoryHandle& handle);
 
   // Returns invalid handle (see comment above for exact definition).
@@ skipping 173 matching lines @@
   size_t             mapped_size_;
   void*              memory_;
   bool               read_only_;
   size_t             requested_size_;
 
   DISALLOW_COPY_AND_ASSIGN(SharedMemory);
 };
 }  // namespace base
 
 #endif  // BASE_MEMORY_SHARED_MEMORY_H_