POSIX: Rewrite IPC's interaction with FileDescriptor

chrome/common/render_messages_internal.h

 // Copyright (c) 2006-2008 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.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
 #include <string>
 #include <vector>
 
 #include "build/build_config.h"
 
 #include "base/clipboard.h"
 #include "base/gfx/rect.h"
 #include "base/gfx/native_widget_types.h"
 #include "base/shared_memory.h"
 #include "chrome/common/ipc_message_macros.h"
-#include "chrome/common/ipc_maybe.h"
 #include "chrome/common/transport_dib.h"
 #include "skia/include/SkBitmap.h"
 #include "webkit/glue/console_message_level.h"
 #include "webkit/glue/dom_operations.h"
 #include "webkit/glue/screen_info.h"
 #include "webkit/glue/webcursor.h"
 #include "webkit/glue/webinputevent.h"
 #include "webkit/glue/webplugin.h"
 
 // TODO(mpcomplete): rename ViewMsg and ViewHostMsg to something that makes
@@ skipping 1150 matching lines @@
                       int /* stream_id */,
                       double /* left_channel */,
                       double /* right_channel */)
 
 #if defined(OS_MACOSX)
   // On OSX, we cannot allocated shared memory from within the sandbox, so
   // this call exists for the renderer to ask the browser to allocate memory
   // on its behalf. We return a file descriptor to the POSIX shared memory.
   IPC_SYNC_MESSAGE_CONTROL1_1(ViewHostMsg_AllocTransportDIB,
                               size_t, /* bytes requested */
-                              IPC::Maybe<TransportDIB::Handle> /* DIB */)
+                              TransportDIB::Handle /* DIB */)
 
   // Since the browser keeps handles to the allocated transport DIBs, this
   // message is sent to tell the browser that it may release them when the
   // renderer is finished with them.
   IPC_MESSAGE_CONTROL1(ViewHostMsg_FreeTransportDIB,
                        TransportDIB::Id /* DIB id */)
 #endif
 
   // A renderer sends this to the browser process when it wants to create a
   // worker.  The browser will create the worker process if necessary, and
   // will return the route id on success.  On error returns MSG_ROUTING_NONE.
   IPC_SYNC_MESSAGE_CONTROL1_1(ViewHostMsg_CreateDedicatedWorker,
                               GURL /* url */,
                               int /* route_id */)
 
   // Wraps an IPC message that's destined to the worker on the renderer->browser
   // hop.
   IPC_MESSAGE_CONTROL1(ViewHostMsg_ForwardToWorker,
                        IPC::Message /* message */)
 
 IPC_END_MESSAGES(ViewHost)