Make Clipboard::FormatType an opaque handle type.

content/common/clipboard_messages.cc

+// Copyright (c) 2011 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.
+
+#include "content/common/clipboard_messages.h"
+
+#include "ui/base/clipboard/clipboard.h"
+
+namespace IPC {
+
+void ParamTraits<ui::Clipboard::FormatType>::Write(
+    Message* m, const param_type& p) {
+  m->WriteString(p.Serialize());
+}
+
+bool ParamTraits<ui::Clipboard::FormatType>::Read(
+    const Message* m, void** iter, param_type* r) {
+  std::string serialization;
+  if (!ReadParam(m, iter, &serialization))
+    return false;
+  *r = ui::Clipboard::FormatType::Deserialize(serialization);
+  return true;
+}
+
+void ParamTraits<ui::Clipboard::FormatType>::Log(
+    const param_type& p, std::string* l) {
+  *l = p.Serialize();
+}
+
+}  // namespace IPC