[Offline Pages] Filtering expired pages and fix consistency check.

components/offline_pages/offline_page_model.h

 // 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.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 39 matching lines @@
   class Observer {
    public:
     // Invoked when the model has finished loading.
     virtual void OfflinePageModelLoaded(OfflinePageModel* model) = 0;
 
     // Invoked when the model is being updated, due to adding, removing or
     // updating an offline page.
     virtual void OfflinePageModelChanged(OfflinePageModel* model) = 0;
 
     // Invoked when an offline copy related to |offline_id| was deleted.
-    // In can be invoked as a result of |CheckForExternalFileDeletion|, if a
-    // deleted page is detected.
     virtual void OfflinePageDeleted(int64_t offline_id,
                                     const ClientId& client_id) = 0;
 
    protected:
     virtual ~Observer() = default;
   };
 
   using CheckPagesExistOfflineResult =
       offline_pages::CheckPagesExistOfflineResult;
   using MultipleOfflinePageItemResult =
@@ skipping 100 matching lines @@
   // selection.
   virtual void GetBestPageForOnlineURL(
       const GURL& online_url,
       const SingleOfflinePageItemCallback callback) = 0;
 
   // Returns an offline page saved for |online_url|. A nullptr is returned if
   // not found.  See |GetBestPageForOnlineURL| for selection criteria.
   virtual const OfflinePageItem* MaybeGetBestPageForOnlineURL(
       const GURL& online_url) const = 0;
 
-  // Checks that all of the offline pages have corresponding offline copies.
+  // Checks that all of the offline pages have corresponding offline copies,
+  // and all archived files have offline pages pointing to them.
   // If a page is discovered to be missing an offline copy, its offline page
-  // metadata will be removed and |OfflinePageDeleted| will be sent to model
-  // observers.
-  virtual void CheckForExternalFileDeletion() = 0;
+  // metadata will be expired. If an archive file is discovered missing its
+  // offline page, it will be deleted.
+  virtual void CheckMetadataConsistency() = 0;
 
   // Marks pages with |offline_ids| as expired and deletes the associated
   // archive files.
   virtual void ExpirePages(const std::vector<int64_t>& offline_ids,
                            const base::Time& expiration_time,
                            const base::Callback<void(bool)>& callback) = 0;
 
   // Returns the policy controller.
   virtual ClientPolicyController* GetPolicyController() = 0;
 
   // TODO(dougarnett): Remove this and its uses.
   virtual bool is_loaded() const = 0;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_