Ntp: show AllDismissedItem when all sections have been dismissed.

components/ntp_snippets/content_suggestions_service.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_CONTENT_SUGGESTIONS_SERVICE_H_
 #define COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 107 matching lines @@
                             const ImageFetchedCallback& callback);
 
   // Dismisses the suggestion with the given |suggestion_id|, if it exists.
   // This will not trigger an update through the observers.
   void DismissSuggestion(const ContentSuggestion::ID& suggestion_id);
 
   // Dismisses the given |category|, if it exists.
   // This will not trigger an update through the observers.
   void DismissCategory(Category category);
 
+  // Restores all dismissed categories.
+  // This will not trigger an update through the observers.
+  void RestoreDismissedCategories();
+
   // Observer accessors.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   // Registers a new ContentSuggestionsProvider. It must be ensured that at most
   // one provider is registered for every category and that this method is
   // called only once per provider.
   void RegisterProvider(std::unique_ptr<ContentSuggestionsProvider> provider);
 
   // Removes history from the specified time range where the URL matches the
@@ skipping 97 matching lines @@
   // are exactly the entries of |categories_| and the values are a subset of
   // |providers_|.
   std::map<Category, ContentSuggestionsProvider*, Category::CompareByID>
       providers_by_category_;
 
   // All current suggestion categories, in an order determined by the
   // |category_factory_|. This vector contains exactly the same categories as
   // |providers_by_category_|.
   std::vector<Category> categories_;
 
+  // All dismissed categories and their providers. These may be restored by
+  // RestoreDismissedCategories().
+  std::map<Category, ContentSuggestionsProvider*, Category::CompareByID>
+      dismissed_providers_by_category_;

[Marc Treib, 2016/10/07 11:40:13]

What's the status of persisting dismissals? Seems like this wouldn't really work
together - we can't persist the provider pointers.

Generally, I'm not too happy with Yet Another data structure storing
categories/providers here... can we just go over all providers instead and
re-register everything?

[Michael van Ouwerkerk, 2016/10/10 16:19:32]

Nicolas is working on persisting section dismissals. As discussed over chat,
keeping a separate data structure centralized in the service seems slightly
preferable to the alternatives of introducing an additional provider state, only
partially undoing what happens in RegisterCategoryIfRequired, or additional
provider / observer plumbing.

+
   // All current suggestions grouped by category. This contains an entry for
   // every category in |categories_| whose status is an available status. It may
   // contain an empty vector if the category is available but empty (or still
   // loading).
   std::map<Category, std::vector<ContentSuggestion>, Category::CompareByID>
       suggestions_by_category_;
 
   // Observer for the HistoryService. All providers are notified when history is
   // deleted.
   ScopedObserver<history::HistoryService, history::HistoryServiceObserver>
       history_service_observer_;
 
   base::ObserverList<Observer> observers_;
 
   const std::vector<ContentSuggestion> no_suggestions_;
 
   // Keep a direct reference to this special provider to redirect scheduling,
   // background fetching and debugging calls to it. If the NTPSnippetsService is
   // loaded, it is also present in |providers_|, otherwise this is a nullptr.
   NTPSnippetsService* ntp_snippets_service_;
 
   UserClassifier user_classifier_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentSuggestionsService);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_