[ABANDONED] Make it possible to send unique_ptr<Value> over IPC/Mojo.

ipc/ipc_message_utils.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 IPC_IPC_MESSAGE_UTILS_H_
 #define IPC_IPC_MESSAGE_UTILS_H_
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
@@ skipping 661 matching lines @@
   typedef base::UnguessableToken param_type;
   static void GetSize(base::PickleSizer* sizer, const param_type& p);
   static void Write(base::Pickle* m, const param_type& p);
   static bool Read(const base::Pickle* m,
                    base::PickleIterator* iter,
                    param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
+struct IPC_EXPORT ParamTraits<std::unique_ptr<base::Value>> {
+  typedef std::unique_ptr<base::Value> param_type;
+  static void GetSize(base::PickleSizer* sizer, const param_type& p);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r);
+  static void Log(const param_type& p, std::string* l);
+};
+
+template <>
 struct ParamTraits<std::tuple<>> {
   typedef std::tuple<> param_type;
   static void GetSize(base::PickleSizer* sizer, const param_type& p) {}
   static void Write(base::Pickle* m, const param_type& p) {}
   static bool Read(const base::Pickle* m,
                    base::PickleIterator* iter,
                    param_type* r) {
     return true;
   }
   static void Log(const param_type& p, std::string* l) {
@@ skipping 256 matching lines @@
       if (!ReadParam(m, iter, &value))
         return false;
     }
     return true;
   }
   static void Log(const param_type& p, std::string* l) {
     l->append("<base::SmallMap>");
   }
 };
 
 template <class P>

[Tom Sepez, 2016/11/03 20:54:50]

Wondering why this partial specialization doesn't work for you.

 struct ParamTraits<std::unique_ptr<P>> {
   typedef std::unique_ptr<P> param_type;
   static void GetSize(base::PickleSizer* sizer, const param_type& p) {
     bool valid = !!p;
     GetParamSize(sizer, valid);
     if (valid)
       GetParamSize(sizer, *p);
   }
   static void Write(base::Pickle* m, const param_type& p) {
     bool valid = !!p;
@@ skipping 183 matching lines @@
 template <class ReplyParamType>
 inline void LogReplyParamsToMessage(const ReplyParamType& reply_params,
                                     const Message* msg) {}
 
 inline void ConnectMessageAndReply(const Message* msg, Message* reply) {}
 #endif
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_UTILS_H_