Get rid of MessageLoop* caching in extensions code.

chrome/browser/download/download_manager.cc

 // Copyright (c) 2006-2009 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/browser/download/download_manager.h"
 
 #include "app/l10n_util.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 1234 matching lines @@
     NotificationService* nservice = NotificationService::current();
       nservice->Notify(NotificationType::EXTENSION_READY_FOR_INSTALL,
                        Source<DownloadManager>(this),
                        NotificationService::NoDetails());
     CrxInstaller::Start(full_path,
                         service->install_directory(),
                         Extension::INTERNAL,
                         "",  // no expected id
                         true,  // please delete crx on completion
                         true,  // privilege increase allowed
-                        g_browser_process->file_thread()->message_loop(),
                         service,
                         new ExtensionInstallUI(profile_));
   }
 }
 
 void DownloadManager::OpenDownloadInShell(const DownloadItem* download,
                                           gfx::NativeView parent_window) {
   DCHECK(file_manager_);
   DCHECK(MessageLoop::current() == ui_loop_);
 #if defined(OS_MACOSX)
@@ skipping 282 matching lines @@
 
   if (contents)
     contents->OnStartDownload(download);
 }
 
 // Clears the last download path, used to initialize "save as" dialogs.
 void DownloadManager::ClearLastDownloadPath() {
   last_download_path_ = FilePath();
 }