POSIX: Rewrite IPC's interaction with FileDescriptor

chrome/renderer/render_process.cc

 // 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.
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <objidl.h>
 #include <mlang.h>
@@ skipping 176 matching lines @@
 #endif
 }
 
 TransportDIB* RenderProcess::CreateTransportDIB(size_t size) {
 #if defined(OS_WIN) || defined(OS_LINUX)
   // Windows and Linux create transport DIBs inside the renderer
   return TransportDIB::Create(size, sequence_number_++);
 #elif defined(OS_MACOSX)  // defined(OS_WIN) || defined(OS_LINUX)
   // Mac creates transport DIBs in the browser, so we need to do a sync IPC to
   // get one.
-  IPC::Maybe<TransportDIB::Handle> mhandle;
-  IPC::Message* msg = new ViewHostMsg_AllocTransportDIB(size, &mhandle);
+  TransportDIB::Handle handle;
+  IPC::Message* msg = new ViewHostMsg_AllocTransportDIB(size, &handle);
   if (!child_thread()->Send(msg))
     return NULL;
-  if (!mhandle.valid)
+  if (handle.fd < 0)
     return NULL;
-  return TransportDIB::Map(mhandle.value);
+  return TransportDIB::Map(handle);
 #endif  // defined(OS_MACOSX)
 }
 
 void RenderProcess::FreeTransportDIB(TransportDIB* dib) {
   if (!dib)
     return;
 
 #if defined(OS_MACOSX)
   // On Mac we need to tell the browser that it can drop a reference to the
   // shared memory.
@@ skipping 83 matching lines @@
 }
 
 void RenderProcess::ClearTransportDIBCache() {
   for (size_t i = 0; i < arraysize(shared_mem_cache_); ++i) {
     if (shared_mem_cache_[i]) {
       FreeTransportDIB(shared_mem_cache_[i]);
       shared_mem_cache_[i] = NULL;
     }
   }
 }