Refactor OfflinePageSuggestionsProvider dismissed ID handling

components/ntp_snippets/offline_pages/offline_page_suggestions_provider.h

 // 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGE_SUGGESTIONS_PROVIDER_H_
 #define COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGE_SUGGESTIONS_PROVIDER_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 71 matching lines @@
       const offline_pages::OfflinePageItem& offline_page) const;
 
   // Gets the |kMaxSuggestionsCount| most recently visited OfflinePageItems from
   // the list, orders them by last visit date and converts them to
   // ContentSuggestions for the |category|.
   std::vector<ContentSuggestion> GetMostRecentlyVisited(
       Category category,
       std::vector<const offline_pages::OfflinePageItem*> offline_page_items)
       const;
 
-  // Reads dismissed IDs from the pref with name |pref_name|.
-  std::set<std::string> ReadDismissedIDsFromPrefs(
-      const std::string& pref_name) const;
+  // Fires the |OnSuggestionInvalidated| event for the suggestion corresponding
+  // to the given |offline_id| and clears it from the dismissed IDs list, if
+  // necessary.
+  void InvalidateSuggestion(Category category, int64_t offline_id);
 
-  // Writes |dismissed_ids| to the pref with name |pref_name|.
-  void StoreDismissedIDsToPrefs(const std::string& pref_name,
+  // Gets the preference name for storing the list of dismissed suggestion IDs
+  // for the given |category|.
+  std::string GetDismissedPref(Category category) const;
+
+  // Reads dismissed IDs for the given |category|.
+  std::set<std::string> ReadDismissedIDsFromPrefs(Category category) const;
+
+  // Writes |dismissed_ids| for the given |category|.
+  void StoreDismissedIDsToPrefs(Category category,
                                 const std::set<std::string>& dismissed_ids);
 
   CategoryStatus recent_tabs_status_;
   CategoryStatus downloads_status_;
 
   offline_pages::OfflinePageModel* offline_page_model_;
 
   const Category recent_tabs_category_;
   const Category downloads_category_;
 
   PrefService* pref_service_;
 
-  std::set<std::string> dismissed_recent_tab_ids_;
-  std::set<std::string> dismissed_download_ids_;
-
   // Whether the Download Manager UI is enabled, in which case the More button
   // for the Downloads section can redirect there.
   const bool download_manager_ui_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageSuggestionsProvider);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGE_SUGGESTIONS_PROVIDER_H_