Stub in more IPC attachment brokering functionality.

ipc/attachment_broker.h

Index: ipc/attachment_broker.h
diff --git a/ipc/attachment_broker.h b/ipc/attachment_broker.h
index 35a638684f7300e1a434462ff9093796e2310441..5b25c236de8d57c6ec63d17686866e4e770d1120 100644
--- a/ipc/attachment_broker.h
+++ b/ipc/attachment_broker.h
@@ -34,7 +34,8 @@ class IPC_EXPORT AttachmentBroker {
   // Sends |attachment| to |destination_process|. The implementation uses an
   // IPC::Channel to communicate with the broker process. This may be the same
   // IPC::Channel that is requesting the brokering of an attachment.
-  virtual void SendAttachmentToProcess(BrokerableAttachment* attachment,
+  // Returns true on success and false otherwise.
+  virtual bool SendAttachmentToProcess(BrokerableAttachment* attachment,
                                        base::ProcessId destination_process) = 0;
 
   // Returns whether the attachment was available. If the attachment was