Revert r21117 as it caused reliability failures....

chrome/utility/utility_thread.cc

 // Copyright (c) 2009 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 "chrome/utility/utility_thread.h"
 
 #include "base/file_util.h"
 #include "base/values.h"
 #include "chrome/common/web_resource/web_resource_unpacker.h"
 #include "chrome/common/child_process.h"
 #include "chrome/common/extensions/extension_unpacker.h"
 #include "chrome/common/render_messages.h"
 
-UtilityThread::UtilityThread() {
-  ChildProcess::current()->AddRefProcess();
+UtilityThread::UtilityThread() : ChildThread(base::Thread::Options()) {
 }
 
 UtilityThread::~UtilityThread() {
 }
 
+void UtilityThread::Init() {
+  ChildThread::Init();
+  ChildProcess::current()->AddRefProcess();
+}
+
+void UtilityThread::CleanUp() {
+  // Shutdown in reverse of the initialization order.
+  ChildThread::CleanUp();
+}
+
 void UtilityThread::OnControlMessageReceived(const IPC::Message& msg) {
   IPC_BEGIN_MESSAGE_MAP(UtilityThread, msg)
     IPC_MESSAGE_HANDLER(UtilityMsg_UnpackExtension, OnUnpackExtension)
     IPC_MESSAGE_HANDLER(UtilityMsg_UnpackWebResource, OnUnpackWebResource)
   IPC_END_MESSAGE_MAP()
 }
 
 void UtilityThread::OnUnpackExtension(const FilePath& extension_path) {
   ExtensionUnpacker unpacker(extension_path);
   if (unpacker.Run() && unpacker.DumpImagesToFile()) {
@@ skipping 15 matching lines @@
     Send(new UtilityHostMsg_UnpackWebResource_Succeeded(
         *unpacker.parsed_json()));
   } else {
     Send(new UtilityHostMsg_UnpackWebResource_Failed(
         unpacker.error_message()));
   }
 
   ChildProcess::current()->ReleaseProcess();
 }