Revert of Make SharedMemoryHandle a class on Mac.

ipc/ipc_message_utils.h

Index: ipc/ipc_message_utils.h
diff --git a/ipc/ipc_message_utils.h b/ipc/ipc_message_utils.h
index 96bb6895abb3f08c25dca3af78c7f8a26619ce38..94651419be23314484f6fe6b91a8d2fc643c1e3e 100644
--- a/ipc/ipc_message_utils.h
+++ b/ipc/ipc_message_utils.h
@@ -57,10 +57,6 @@
 class TimeTicks;
 class TraceTicks;
 struct FileDescriptor;
-
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-class SharedMemoryHandle;
-#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 }
 
 namespace IPC {
@@ -471,16 +467,6 @@
 };
 #endif  // defined(OS_POSIX)
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-template <>
-struct IPC_EXPORT ParamTraits<base::SharedMemoryHandle> {
-  typedef base::SharedMemoryHandle param_type;
-  static void Write(Message* m, const param_type& p);
-  static bool Read(const Message* m, base::PickleIterator* iter, param_type* r);
-  static void Log(const param_type& p, std::string* l);
-};
-#endif
-
 template <>
 struct IPC_EXPORT ParamTraits<base::FilePath> {
   typedef base::FilePath param_type;