POSIX: Rewrite IPC's interaction with FileDescriptor

The FileDescriptor API is clearly too hard to use. It's the only IPC
data type which is non-POD and serialising an invalid file descriptor
is fatal to Chrome on POSIX. The use of Maybe is possibly non-obvious
to non-functional programmers.

This patch merges Maybe and FileDescriptor so that serialising invalid
file descriptors is permitted and results in -1 at the other end.
(Serialising /closed/ a file descriptor is still fatal.) Also, it adds
a pointer in base/file_descriptor.h to instructions for its use with
IPC. Although it's generally bad practice to mention IPC in base, in
this case I cannot find another suitable location.

Review URL: http://codereview.chromium.org/39208


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@11041 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 4 deletions

diff --git a/chrome/renderer/render_process.cc b/chrome/renderer/render_process.cc
index 99b91fa..b10042b 100644
--- a/chrome/renderer/render_process.cc
+++ b/chrome/renderer/render_process.cc
@@ -190,13 +190,13 @@ TransportDIB* RenderProcess::CreateTransportDIB(size_t size) {
 #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)
 }