Use WebIDBKeyPath type in WebKit API, implement IndexedDBKeyPath type.

content/common/indexed_db/indexed_db_param_traits.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 CONTENT_COMMON_INDEXED_DB_INDEXED_DB_PARAM_TRAITS_H_
 #define CONTENT_COMMON_INDEXED_DB_INDEXED_DB_PARAM_TRAITS_H_
 #pragma once
 
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_param_traits.h"
 
 class IndexedDBKey;
 class IndexedDBKeyRange;
 
 namespace content {
+class IndexedDBKeyPath;
 class SerializedScriptValue;
 }
 
 namespace IPC {
 
 // These datatypes are used by utility_messages.h and render_messages.h.
 // Unfortunately we can't move it to common: MSVC linker complains about
 // WebKit datatypes that are not linked on npchrome_frame (even though it's
 // never actually used by that target).
 
 template <>
 struct ParamTraits<content::SerializedScriptValue> {
   typedef content::SerializedScriptValue param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
 struct ParamTraits<IndexedDBKey> {
   typedef IndexedDBKey param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
+struct ParamTraits<content::IndexedDBKeyPath> {
+  typedef content::IndexedDBKeyPath param_type;
+  static void Write(Message* m, const param_type& p);
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r);
+  static void Log(const param_type& p, std::string* l);
+};
+
+template <>
 struct ParamTraits<IndexedDBKeyRange> {
   typedef IndexedDBKeyRange param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 } // namespace IPC
 
 #endif  // CONTENT_COMMON_INDEXED_DB_INDEXED_DB_PARAM_TRAITS_H_