Stub in more IPC attachment brokering functionality.

ipc/ipc_message_attachment_set.h

Index: ipc/ipc_message_attachment_set.h
diff --git a/ipc/ipc_message_attachment_set.h b/ipc/ipc_message_attachment_set.h
index 7e848bd3f544207c35f117f5cd06b7055c51e710..bd113012aff5507f40e31720346797165755db1b 100644
--- a/ipc/ipc_message_attachment_set.h
+++ b/ipc/ipc_message_attachment_set.h
@@ -18,6 +18,7 @@
 
 namespace IPC {
 
+class BrokerableAttachment;
 class MessageAttachment;
 
 // -----------------------------------------------------------------------------
@@ -37,6 +38,8 @@ class IPC_EXPORT MessageAttachmentSet
   unsigned num_descriptors() const;
   // Return the number of mojo handles in the attachment set
   unsigned num_mojo_handles() const;
+  // Return the number of brokerable attachments in the attachment set.
+  unsigned num_brokerable_attachments() const;
 
   // Return true if no unconsumed descriptors remain
   bool empty() const { return 0 == size(); }
@@ -56,6 +59,9 @@ class IPC_EXPORT MessageAttachmentSet
   // which are auto-close.
   void CommitAll();
 
+  // Returns a vector of all brokerable attachments.
+  std::vector<const BrokerableAttachment*> PeekBrokerableAttachments() const;
+
 #if defined(OS_POSIX)
   // This is the maximum number of descriptors per message. We need to know this
   // because the control message kernel interface has to be given a buffer which