Implement the gamepad API in the IPC proxy

ppapi/proxy/ppapi_messages.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.
 
 // Multiply-included message header, no traditional include guard.
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
@@ skipping 1533 matching lines @@
 IPC_MESSAGE_CONTROL4(PpapiHostMsg_FileChooser_Show,
                      bool /* save_as */,
                      bool /* open_multiple */,
                      std::string /* suggested_file_name */,
                      std::vector<std::string> /* accept_mime_types */)
 IPC_MESSAGE_CONTROL1(PpapiPluginMsg_FileChooser_ShowReply,
                      std::vector<ppapi::PPB_FileRef_CreateInfo> /* files */)
 
 // Gamepad.
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_Gamepad_Create)
+
+// Requests that the gamepad host send the shared memory handle to the plugin
+// process.
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_Gamepad_RequestMemory)
-IPC_MESSAGE_CONTROL1(PpapiPluginMsg_Gamepad_SendMemory,
-                     base::SharedMemoryHandle /* handle */)
+
+// Reply to a RequestMemory call. This supplies the shared memory handle. The
+// actual handle is passed in the ReplyParams struct.
+IPC_MESSAGE_CONTROL0(PpapiPluginMsg_Gamepad_SendMemory)
+
 // Printing.
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_Printing_Create)
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_Printing_GetDefaultPrintSettings)
 IPC_MESSAGE_CONTROL1(PpapiPluginMsg_Printing_GetDefaultPrintSettingsReply,
                      PP_PrintSettings_Dev /* print_settings */)