Stub in more IPC attachment brokering functionality.

ipc/ipc_channel_win.cc

Index: ipc/ipc_channel_win.cc
diff --git a/ipc/ipc_channel_win.cc b/ipc/ipc_channel_win.cc
index 0e603195f3e23bf32765614c3b3595ee30f486f4..cff0f4b6752e91ce2e4b5d10dc5b49d79e66c06b 100644
--- a/ipc/ipc_channel_win.cc
+++ b/ipc/ipc_channel_win.cc
@@ -19,6 +19,7 @@
 #include "base/win/scoped_handle.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_logging.h"
+#include "ipc/ipc_message_attachment_set.h"
 #include "ipc/ipc_message_utils.h"
 
 namespace IPC {
@@ -81,12 +82,28 @@ void ChannelWin::Close() {
 }
 
 bool ChannelWin::Send(Message* message) {
+  // TODO(erikchen): Remove this DCHECK once ChannelWin fully supports
+  // brokerable attachments. http://crbug.com/493414.
   DCHECK(!message->HasAttachments());
   DCHECK(thread_check_->CalledOnValidThread());
   DVLOG(2) << "sending message @" << message << " on channel @" << this
            << " with type " << message->type()
            << " (" << output_queue_.size() << " in queue)";
 
+  // Sending a brokerable attachment requires a call to Channel::Send(), so
+  // Send() may be re-entrant. Brokered attachments must be sent before the
+  // Message itself.
+  if (message->HasBrokerableAttachments()) {
+    DCHECK(broker_);
+    for (scoped_refptr<BrokerableAttachment> attachment :

[Tom Sepez, 2015/06/19 18:04:11]

Are we sure this doesn't do needless ref/dererf on each call?  Does using
scoped_refptr<BrokerableAttachment>& instead fix this? Can we use a const
reference too?

Hope to simplify to |for (const auto& attachment : ...) {|

[erikchen, 2015/06/23 22:37:00]

As per your later suggestion, I changed the interface to MessageAttachmentSet to
return a vector of raw pointers instead of scoped_refptrs to avoid the otherwise
unnecessary ref/deref.
I chan

+         message->attachment_set()->PeekBrokerableAttachments()) {
+      bool success =

[Tom Sepez, 2015/06/19 18:04:11]

nit: no need for local.

[erikchen, 2015/06/23 22:37:00]

I've removed it.

+          broker_->SendAttachmentToProcess(attachment.get(), peer_pid_);

[Tom Sepez, 2015/06/19 18:04:11]

nit: local var not needed.

[erikchen, 2015/06/23 22:37:00]

Done.

+      if (!success)
+        return false;
+    }
+  }
+
 #ifdef IPC_MESSAGE_LOG_ENABLED
   Logging::GetInstance()->OnSendMessage(message, "");
 #endif