Revert of IPC: Add attachment brokering support to the message header.

ipc/ipc_message_attachment_set.cc

Index: ipc/ipc_message_attachment_set.cc
diff --git a/ipc/ipc_message_attachment_set.cc b/ipc/ipc_message_attachment_set.cc
index 6a8024fe9e6f019606f2172e35f878eda2ba47cb..1a4969f505159d318d0b7d684d8368863da49f12 100644
--- a/ipc/ipc_message_attachment_set.cc
+++ b/ipc/ipc_message_attachment_set.cc
@@ -143,25 +143,17 @@
   return output;
 }
 
-void MessageAttachmentSet::ReplacePlaceholderWithAttachment(
-    const scoped_refptr<BrokerableAttachment>& attachment) {
-  for (auto it = attachments_.begin(); it != attachments_.end(); ++it) {
-    if ((*it)->GetType() != MessageAttachment::TYPE_BROKERABLE_ATTACHMENT)
-      continue;
-    BrokerableAttachment* brokerable_attachment =
-        static_cast<BrokerableAttachment*>(it->get());
-
-    if (brokerable_attachment->GetBrokerableType() ==
-            BrokerableAttachment::PLACEHOLDER &&
-        brokerable_attachment->GetIdentifier() == attachment->GetIdentifier()) {
-      *it = attachment;
-      return;
+std::vector<scoped_refptr<BrokerableAttachment>>
+MessageAttachmentSet::GetBrokerableAttachmentsForUpdating() {
+  std::vector<scoped_refptr<BrokerableAttachment>> output;
+  for (const scoped_refptr<MessageAttachment>& attachment : attachments_) {
+    if (attachment->GetType() ==
+        MessageAttachment::TYPE_BROKERABLE_ATTACHMENT) {
+      output.push_back(scoped_refptr<BrokerableAttachment>(
+          static_cast<BrokerableAttachment*>(attachment.get())));
     }
   }
-
-  // This function should only be called if there is a placeholder ready to be
-  // replaced.
-  NOTREACHED();
+  return output;
 }
 
 #if defined(OS_POSIX)