Fix an attachment broker race condition.

ipc/attachment_broker.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/attachment_broker.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 82 matching lines @@
 
 void AttachmentBroker::RegisterBrokerCommunicationChannel(Endpoint* endpoint) {
   NOTREACHED();
 }
 
 void AttachmentBroker::DeregisterBrokerCommunicationChannel(
     Endpoint* endpoint) {
   NOTREACHED();
 }
 
+void AttachmentBroker::ReceivedPeerPid(base::ProcessId peer_pid) {
+  NOTREACHED();
+}
+
 bool AttachmentBroker::IsPrivilegedBroker() {
   NOTREACHED();
   return false;
 }
 
 void AttachmentBroker::HandleReceivedAttachment(
     const scoped_refptr<BrokerableAttachment>& attachment) {
   {
     base::AutoLock auto_lock(*get_lock());
     attachments_.push_back(attachment);
@@ skipping 35 matching lines @@
 
   observer->ReceivedBrokerableAttachmentWithId(id);
 }
 
 AttachmentBroker::ObserverInfo::ObserverInfo() {}
 AttachmentBroker::ObserverInfo::ObserverInfo(const ObserverInfo& other) =
     default;
 AttachmentBroker::ObserverInfo::~ObserverInfo() {}
 
 }  // namespace IPC