IPC fuzzer: create message_lib library.

tools/ipc_fuzzer/message_lib/message_cracker.h

+// Copyright 2013 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 TOOLS_IPC_FUZZER_MESSAGE_LIB_MESSAGE_CRACKER_H_
+#define TOOLS_IPC_FUZZER_MESSAGE_LIB_MESSAGE_CRACKER_H_
+
+#include <string.h>
+#include "ipc/ipc_message.h"
+
+// Means for updating protected message fields.
+class MessageCracker : public IPC::Message {
+ public:
+  static void CopyMessageID(IPC::Message* dst, IPC::Message* src) {
+    memcpy(ToCracker(dst)->mutable_payload(),
+           ToCracker(src)->payload(),
+           sizeof(int));
+  }
+
+  static void SetMessageType(IPC::Message* message, uint32 type) {
+    ToCracker(message)->header()->type = type;
+  }
+
+ private:
+  static MessageCracker* ToCracker(IPC::Message* message) {
+    return reinterpret_cast<MessageCracker*>(message);
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(MessageCracker);
+};
+
+#endif  // TOOLS_IPC_FUZZER_MESSAGE_LIB_MESSAGE_CRACKER_H_