New snippets now replace old snippets and do not merge

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 194 matching lines @@
                      const std::set<GURL>& favicon_urls) override;
   void HistoryServiceBeingDeleted(
       history::HistoryService* history_service) override;
 
   // Registers the given |provider| for the given |category|, unless it is
   // already registered. Returns true if the category was newly registered or
   // false if it was present before.
   bool RegisterCategoryIfRequired(ContentSuggestionsProvider* provider,
                                   Category category);
 
-  // Removes a suggestion from the local stores |id_category_map_| and
-  // |suggestions_by_category_|, if it exists. Returns true if a suggestion was
-  // removed.
+  // Removes a suggestion from the local store |suggestions_by_category_|, if it
+  // exists. Returns true if a suggestion was removed.
   bool RemoveSuggestionByID(Category category,
                             const std::string& suggestion_id);
 
   // Fires the OnCategoryStatusChanged event for the given |category|.
   void NotifyCategoryStatusChanged(Category category);
 
   void SortCategories();
 
   // Whether the content suggestions feature is enabled.
   State state_;
@@ skipping 16 matching lines @@
   // |providers_by_category_|.
   std::vector<Category> categories_;
 
   // 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_;
 
-  // Map used to determine the category of a suggestion (of which only the ID
-  // is available). This also determines the provider that delivered the
-  // suggestion.
-  std::map<std::string, Category> id_category_map_;
-
   // 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_