Add missing locking for the |sender_| member in IPC::SyncMessageFilter.

ipc/ipc_sync_message_filter.cc

 // Copyright (c) 2012 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/ipc_sync_message_filter.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 53 matching lines @@
   {
     base::AutoLock auto_lock(lock_);
     delete pending_message.deserializer;
     pending_sync_messages_.erase(&pending_message);
   }
 
   return pending_message.send_result;
 }
 
 void SyncMessageFilter::OnFilterAdded(Sender* sender) {
-  sender_ = sender;
   std::vector<Message*> pending_messages;
   {
     base::AutoLock auto_lock(lock_);
+    sender_ = sender;
     io_task_runner_ = base::ThreadTaskRunnerHandle::Get();
     pending_messages_.release(&pending_messages);
   }
   for (auto* msg : pending_messages)
     SendOnIOThread(msg);
 }
 
 void SyncMessageFilter::OnChannelError() {
+  base::AutoLock auto_lock(lock_);
   sender_ = NULL;
   SignalAllEvents();
 }
 
 void SyncMessageFilter::OnChannelClosing() {
+  base::AutoLock auto_lock(lock_);
   sender_ = NULL;
   SignalAllEvents();
 }
 
 bool SyncMessageFilter::OnMessageReceived(const Message& message) {
   base::AutoLock auto_lock(lock_);
   for (PendingSyncMessages::iterator iter = pending_sync_messages_.begin();
        iter != pending_sync_messages_.end(); ++iter) {
     if (SyncMessage::IsMessageReplyTo(message, (*iter)->id)) {
       if (!message.is_reply_error()) {
@@ skipping 21 matching lines @@
 
 void SyncMessageFilter::SendOnIOThread(Message* message) {
   if (sender_) {
     sender_->Send(message);
     return;
   }
 
   if (message->is_sync()) {
     // We don't know which thread sent it, but it doesn't matter, just signal
     // them all.
+    base::AutoLock auto_lock(lock_);
     SignalAllEvents();
   }
 
   delete message;
 }
 
 void SyncMessageFilter::SignalAllEvents() {
-  base::AutoLock auto_lock(lock_);
+  lock_.AssertAcquired();
   for (PendingSyncMessages::iterator iter = pending_sync_messages_.begin();
        iter != pending_sync_messages_.end(); ++iter) {
     (*iter)->done_event->Signal();
   }
 }
 
 }  // namespace IPC