Remove all remaining traces of MessageLoopProxy.

extensions/browser/api/serial/serial_service_factory.cc

 // Copyright 2015 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 "extensions/browser/api/serial/serial_service_factory.h"
 
 #include <utility>
 
 #include "content/public/browser/browser_thread.h"
 #include "device/serial/serial_service_impl.h"
 
 namespace extensions {
 namespace {
 const base::Callback<void(
     mojo::InterfaceRequest<device::serial::SerialService>)>*
     g_serial_service_test_factory = nullptr;
 }
 
 void BindToSerialServiceRequest(
     mojo::InterfaceRequest<device::serial::SerialService> request) {
   if (g_serial_service_test_factory) {
     g_serial_service_test_factory->Run(std::move(request));
     return;
   }
   device::SerialServiceImpl::CreateOnMessageLoop(
-      content::BrowserThread::GetMessageLoopProxyForThread(
+      content::BrowserThread::GetTaskRunnerForThread(
           content::BrowserThread::FILE),
-      content::BrowserThread::GetMessageLoopProxyForThread(
+      content::BrowserThread::GetTaskRunnerForThread(
           content::BrowserThread::IO),
-      content::BrowserThread::GetMessageLoopProxyForThread(
+      content::BrowserThread::GetTaskRunnerForThread(
           content::BrowserThread::UI),
       std::move(request));
 }
 
 void SetSerialServiceFactoryForTest(const base::Callback<
     void(mojo::InterfaceRequest<device::serial::SerialService>)>* callback) {
   g_serial_service_test_factory = callback;
 }
 
 }  // namespace extensions