ipc: Add a lock to guard modifications of state of the AttachmentBroker.

ipc/attachment_broker_privileged.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_privileged.h"
 
 #include <algorithm>
 
 #include "base/lazy_instance.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 69 matching lines @@
 }
 #else
 // static
 void AttachmentBrokerPrivileged::CreateBrokerIfNeeded() {
   g_attachment_broker_make_once.Get();
 }
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 
 void AttachmentBrokerPrivileged::RegisterCommunicationChannel(
     Endpoint* endpoint) {
+  base::AutoLock auto_lock(*get_lock());
   endpoint->SetAttachmentBrokerEndpoint(true);
   auto it = std::find(endpoints_.begin(), endpoints_.end(), endpoint);
   DCHECK(endpoints_.end() == it);
   endpoints_.push_back(endpoint);
 }
 
 void AttachmentBrokerPrivileged::DeregisterCommunicationChannel(
     Endpoint* endpoint) {
+  base::AutoLock auto_lock(*get_lock());
   auto it = std::find(endpoints_.begin(), endpoints_.end(), endpoint);
   if (it != endpoints_.end())
     endpoints_.erase(it);
 }
 
 Sender* AttachmentBrokerPrivileged::GetSenderWithProcessId(base::ProcessId id) {
+  base::AutoLock auto_lock(*get_lock());
   auto it = std::find_if(endpoints_.begin(), endpoints_.end(),
                          [id](Endpoint* c) { return c->GetPeerPID() == id; });
   if (it == endpoints_.end())
     return nullptr;
   return *it;
 }
 
 void AttachmentBrokerPrivileged::LogError(UMAError error) {
   UMA_HISTOGRAM_ENUMERATION(
       "IPC.AttachmentBrokerPrivileged.BrokerAttachmentError", error, ERROR_MAX);
 }
 
 }  // namespace IPC