Land http://codereview.chromium.org/159067:

ipc/ipc_message_utils.h

 // 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 IPC_IPC_MESSAGE_UTILS_H_
 #define IPC_IPC_MESSAGE_UTILS_H_
 
 #include <string>
 #include <vector>
 #include <map>
@@ skipping 82 matching lines @@
     }
   }
  private:
   const Message& msg_;
   mutable void* iter_;
 };
 
 //-----------------------------------------------------------------------------
 // ParamTraits specializations, etc.
 
-template <class P> struct ParamTraits {};
+template <class P> struct ParamTraits {
+};
+
+template <class P>
+struct SimilarTypeTraits {
+  typedef P Type;
+};
 
 template <class P>
 static inline void WriteParam(Message* m, const P& p) {
-  ParamTraits<P>::Write(m, p);
+  typedef typename SimilarTypeTraits<P>::Type Type;
+  ParamTraits<Type>::Write(m, static_cast<const Type& >(p));
 }
 
 template <class P>
 static inline bool WARN_UNUSED_RESULT ReadParam(const Message* m, void** iter,
                                                 P* p) {
-  return ParamTraits<P>::Read(m, iter, p);
+  typedef typename SimilarTypeTraits<P>::Type Type;
+  return ParamTraits<Type>::Read(m, iter, reinterpret_cast<Type* >(p));
 }
 
 template <class P>
 static inline void LogParam(const P& p, std::wstring* l) {
-  ParamTraits<P>::Log(p, l);
+  typedef typename SimilarTypeTraits<P>::Type Type;
+  ParamTraits<Type>::Log(static_cast<const Type& >(p), l);
 }
 
 template <>
 struct ParamTraits<bool> {
   typedef bool param_type;
   static void Write(Message* m, const param_type& p) {
     m->WriteBool(p);
   }
   static bool Read(const Message* m, void** iter, param_type* r) {
     return m->ReadBool(iter, r);
@@ skipping 652 matching lines @@
       ReadParam(m, iter, &r->dispatch) &&
       ReadParam(m, iter, &r->params);
     r->type = static_cast<uint16>(type);
     return result;
   }
   static void Log(const param_type& p, std::wstring* l) {
     // Doesn't make sense to implement this!
   }
 };
 
-
 template <>
 struct ParamTraits<Message> {
   static void Write(Message* m, const Message& p) {
     m->WriteInt(p.size());
     m->WriteData(reinterpret_cast<const char*>(p.data()), p.size());
   }
   static bool Read(const Message* m, void** iter, Message* r) {
     int size;
     if (!m->ReadInt(iter, &size))
       return false;
@@ skipping 423 matching lines @@
     ReplyParam p(a, b, c, d, e);
     WriteParam(reply, p);
   }
 };
 
 //-----------------------------------------------------------------------------
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_UTILS_H_