[ew] Simplify the entry watcher logic.

chrome/browser/extensions/api/file_system/entry_watcher_service_factory.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/extensions/api/file_system/entry_watcher_service_factory.h"
-
-#include "chrome/browser/extensions/api/file_system/entry_watcher_service.h"
-#include "chrome/browser/profiles/profile.h"
-#include "components/keyed_service/content/browser_context_dependency_manager.h"
-#include "content/public/browser/browser_context.h"
-
-namespace extensions {
-
-EntryWatcherServiceFactory* EntryWatcherServiceFactory::GetInstance() {
-  return Singleton<EntryWatcherServiceFactory>::get();
-}
-
-EntryWatcherServiceFactory::EntryWatcherServiceFactory()
-    : BrowserContextKeyedServiceFactory(
-          "EntryWatcherService",
-          BrowserContextDependencyManager::GetInstance()) {
-}
-
-EntryWatcherServiceFactory::~EntryWatcherServiceFactory() {
-}
-
-KeyedService* EntryWatcherServiceFactory::BuildServiceInstanceFor(
-    content::BrowserContext* context) const {
-  return new EntryWatcherService(Profile::FromBrowserContext(context));
-}
-
-bool EntryWatcherServiceFactory::ServiceIsCreatedWithBrowserContext() const {
-  // Required to restore persistent watchers as soon as the profile is loaded.
-  return true;
-}
-
-}  // namespace extensions