[Offline pages] Extracting callbacks from the Offline Page Model

components/offline_pages/offline_page_storage_manager.cc

 // Copyright 2016 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/offline_pages/offline_page_storage_manager.h"
 
 #include "base/bind.h"
 #include "components/offline_pages/client_policy_controller.h"
 #include "components/offline_pages/offline_page_client_policy.h"
 #include "components/offline_pages/offline_page_item.h"
 #include "components/offline_pages/offline_page_model.h"
 
-using DeletePageResult = offline_pages::OfflinePageModel::DeletePageResult;
-using MultipleOfflinePageItemResult =
-    offline_pages::OfflinePageModel::MultipleOfflinePageItemResult;
-
 namespace offline_pages {
 
 OfflinePageStorageManager::OfflinePageStorageManager(OfflinePageModel* model)
     : model_(model),
       policy_controller_(model->GetPolicyController()),
       in_progress_(false),
       weak_ptr_factory_(this) {}
 
 OfflinePageStorageManager::~OfflinePageStorageManager() {
 }
@@ skipping 41 matching lines @@
 }
 
 bool OfflinePageStorageManager::IsPageExpired(const OfflinePageItem& page) {
   base::Time now = base::Time::Now();
   const LifetimePolicy& policy =
       policy_controller_->GetPolicy(page.client_id.name_space).lifetime_policy;
   return now - page.last_access_time > policy.expiration_period;
 }
 
 }  // namespace offline_pages