Always destroy CrxInstaller on the UI Thread

chrome/browser/chromeos/app_mode/kiosk_external_update_validator.cc

 // Copyright 2014 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/chromeos/app_mode/kiosk_external_update_validator.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "content/public/browser/browser_thread.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest_constants.h"
 
 namespace chromeos {
 
 KioskExternalUpdateValidator::KioskExternalUpdateValidator(
     const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner,
     const extensions::CRXFileInfo& file,
     const base::FilePath& crx_unpack_dir,
     const base::WeakPtr<KioskExternalUpdateValidatorDelegate>& delegate)
-    : backend_task_runner_(backend_task_runner),
+    : SandboxedUnpackerClient(
+          content::BrowserThread::GetMessageLoopProxyForThread(
+              content::BrowserThread::UI)),
+      backend_task_runner_(backend_task_runner),
       crx_file_(file),
       crx_unpack_dir_(crx_unpack_dir),
       delegate_(delegate) {
 }
 
 KioskExternalUpdateValidator::~KioskExternalUpdateValidator() {
 }
 
 void KioskExternalUpdateValidator::Start() {
   scoped_refptr<extensions::SandboxedUnpacker> unpacker(
@@ skipping 38 matching lines @@
 
   content::BrowserThread::PostTask(
       content::BrowserThread::UI, FROM_HERE,
       base::Bind(
           &KioskExternalUpdateValidatorDelegate::OnExtenalUpdateUnpackSuccess,
           delegate_, crx_file_.extension_id, extension->VersionString(),
           minimum_browser_version, temp_dir));
 }
 
 }  // namespace chromeos