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, 5 insertions, 5 deletions

diff --git a/chrome/browser/renderer_host/render_widget_helper.cc b/chrome/browser/renderer_host/render_widget_helper.cc
index 715a85b..24e1710 100644
--- a/chrome/browser/renderer_host/render_widget_helper.cc
+++ b/chrome/browser/renderer_host/render_widget_helper.cc
@@ -263,21 +263,21 @@ TransportDIB* RenderWidgetHelper::MapTransportDIB(TransportDIB::Id dib_id) {
 }
 
 void RenderWidgetHelper::AllocTransportDIB(
-    size_t size, IPC::Maybe<TransportDIB::Handle>* result) {
+    size_t size, TransportDIB::Handle* result) {
   base::SharedMemory* shared_memory = new base::SharedMemory();
   if (!shared_memory->Create(L"", false /* read write */,
                              false /* do not open existing */, size)) {
-    result->valid = false;
+    result->fd = -1;
+    result->auto_close = false;
     delete shared_memory;
     return;
   }
 
-  result->valid = true;
-  shared_memory->GiveToProcess(0 /* pid, not needed */, &result->value);
+  shared_memory->GiveToProcess(0 /* pid, not needed */, result);
 
   // Keep a copy of the file descriptor around
   AutoLock locked(allocated_dibs_lock_);
-  allocated_dibs_[shared_memory->id()] = dup(result->value.fd);
+  allocated_dibs_[shared_memory->id()] = dup(result->fd);
 }
 
 void RenderWidgetHelper::FreeTransportDIB(TransportDIB::Id dib_id) {