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..efa35eddbcc166bd441a40ce9d47cbae8ede55b2 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 +59,10 @@ class IPC_EXPORT MessageAttachmentSet
   // which are auto-close.
   void CommitAll();
 
+  // Returns a vector of all brokerable attachments.
+  std::vector<scoped_refptr<BrokerableAttachment>> PeekBrokerableAttachments()

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

nit: maybe want an interface that doesn't copy all these and increment ref
counts?

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

I changed the interface to return a vector of raw pointers.

(I want the returned type to be BrokerableAttachment rather than
MessageAttachment, so there's no way to return a reference to the existing
objects.)

+      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