[Doodle] Make DoodleService a KeyedService and add a factory

components/doodle/doodle_service.cc

 // Copyright 2017 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 "components/doodle/doodle_service.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/time/time.h"
@@ skipping 29 matching lines @@
 
   base::Time expiry_date = base::Time::FromInternalValue(
       pref_service_->GetInt64(prefs::kCachedConfigExpiry));
   base::Optional<DoodleConfig> config = DoodleConfig::FromDictionary(
       *pref_service_->GetDictionary(prefs::kCachedConfig), base::nullopt);
   UpdateCachedConfig(expiry_date - clock_->Now(), config);
 }
 
 DoodleService::~DoodleService() = default;
 
+void DoodleService::Shutdown() {}
+
 void DoodleService::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 
 void DoodleService::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
 void DoodleService::Refresh() {
   fetcher_->FetchDoodle(
@@ skipping 46 matching lines @@
     expiry_timer_->Stop();
   }
 }
 
 void DoodleService::DoodleExpired() {
   DCHECK(cached_config_.has_value());
   UpdateCachedConfig(base::TimeDelta(), base::nullopt);
 }
 
 }  // namespace doodle