Fix HidService lifetime issues

extensions/shell/browser/api/shell_extensions_api_client.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 "extensions/shell/browser/api/shell_extensions_api_client.h"
-
-#include "content/public/browser/browser_thread.h"
-#include "device/hid/hid_service.h"
-
-namespace extensions {
-
-ShellExtensionsAPIClient::ShellExtensionsAPIClient() {
-}
-
-ShellExtensionsAPIClient::~ShellExtensionsAPIClient() {
-}
-
-device::HidService* ShellExtensionsAPIClient::GetHidService() {
-  if (!hid_service_) {
-    hid_service_.reset(device::HidService::Create(
-        content::BrowserThread::GetMessageLoopProxyForThread(
-            content::BrowserThread::UI)));
-  }
-  return hid_service_.get();
-}
-
-}  // namespace extensions