Make Clipboard::FormatType an opaque handle type.

content/common/clipboard_messages.h

 // 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.
 
 // Multiply-included message file, so no include guard.
 
 #include <string>
 #include <vector>
 
 #include "base/shared_memory.h"
 #include "content/public/common/common_param_traits.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_param_traits.h"
 #include "ui/base/clipboard/clipboard.h"
 
 #define IPC_MESSAGE_START ClipboardMsgStart
 
+#ifndef CONTENT_COMMON_CLIPBOARD_MESSAGES_H_
+#define CONTENT_COMMON_CLIPBOARD_MESSAGES_H_
+
+namespace IPC {
+
+template<>
+struct ParamTraits<ui::Clipboard::FormatType> {
+  typedef ui::Clipboard::FormatType param_type;
+  static void Write(Message* m, const param_type& p);
+  static bool Read(const Message* m, void** iter, param_type* r);
+  static void Log(const param_type& p, std::string* l);
+};
+
+}  // namespace IPC
+
+#endif  // CONTENT_COMMON_CLIPBOARD_MESSAGES_H_
+
 IPC_ENUM_TRAITS(ui::Clipboard::Buffer)
 
 // Clipboard IPC messages sent from the renderer to the browser.
 
 // This message is used when the object list does not contain a bitmap.
 IPC_MESSAGE_CONTROL1(ClipboardHostMsg_WriteObjectsAsync,
                      ui::Clipboard::ObjectMap /* objects */)
 // This message is used when the object list contains a bitmap.
 // It is synchronized so that the renderer knows when it is safe to
 // free the shared memory used to transfer the bitmap.
 IPC_SYNC_MESSAGE_CONTROL2_0(ClipboardHostMsg_WriteObjectsSync,
                             ui::Clipboard::ObjectMap /* objects */,
                             base::SharedMemoryHandle /* bitmap handle */)
 IPC_SYNC_MESSAGE_CONTROL1_1(ClipboardHostMsg_GetSequenceNumber,
                             ui::Clipboard::Buffer /* buffer */,
                             uint64 /* result */)
 IPC_SYNC_MESSAGE_CONTROL2_1(ClipboardHostMsg_IsFormatAvailable,
-                            std::string /* format */,
+                            ui::Clipboard::FormatType /* format */,
                             ui::Clipboard::Buffer /* buffer */,
                             bool /* result */)
 IPC_SYNC_MESSAGE_CONTROL1_2(ClipboardHostMsg_ReadAvailableTypes,
                             ui::Clipboard::Buffer /* buffer */,
                             std::vector<string16> /* types */,
                             bool /* contains filenames */)
 IPC_SYNC_MESSAGE_CONTROL1_1(ClipboardHostMsg_ReadText,
                             ui::Clipboard::Buffer /* buffer */,
                             string16 /* result */)
 IPC_SYNC_MESSAGE_CONTROL1_1(ClipboardHostMsg_ReadAsciiText,
@@ skipping 11 matching lines @@
                             uint32 /* image size */)
 IPC_SYNC_MESSAGE_CONTROL2_1(ClipboardHostMsg_ReadCustomData,
                             ui::Clipboard::Buffer /* buffer */,
                             string16 /* type */,
                             string16 /* result */)
 
 #if defined(OS_MACOSX)
 IPC_MESSAGE_CONTROL1(ClipboardHostMsg_FindPboardWriteStringAsync,
                      string16 /* text */)
 #endif