Remove the mojo serial interfaces and related infrastructure.

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::GetTaskRunnerForThread(
-          content::BrowserThread::FILE),
-      content::BrowserThread::GetTaskRunnerForThread(
-          content::BrowserThread::IO),
-      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