Fix race condition in utility process clients

content/browser/utility_process_host.cc

 // Copyright (c) 2011 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 "content/browser/utility_process_host.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/message_loop.h"
@@ skipping 35 matching lines @@
 #else
       child_flags_(ChildProcessHost::CHILD_NORMAL),
 #endif
       use_linux_zygote_(false),
       started_(false) {
   process_.reset(
       new BrowserChildProcessHostImpl(content::PROCESS_TYPE_UTILITY, this));
 }
 
 UtilityProcessHost::~UtilityProcessHost() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK(!is_batch_mode_);
 }
 
 bool UtilityProcessHost::Send(IPC::Message* message) {
   if (!StartProcess())
     return false;
 
   return process_->Send(message);
 }
 
@@ skipping 90 matching lines @@
       base::Bind(base::IgnoreResult(&Client::OnMessageReceived),
                  client_.get(), message));
   return true;
 }
 
 void UtilityProcessHost::OnProcessCrashed(int exit_code) {
   BrowserThread::PostTask(
       client_thread_id_, FROM_HERE,
       base::Bind(&Client::OnProcessCrashed, client_.get(), exit_code));
 }