New snippets now replace old snippets and do not merge

components/ntp_snippets/content_suggestions_service.h

Index: components/ntp_snippets/content_suggestions_service.h
diff --git a/components/ntp_snippets/content_suggestions_service.h b/components/ntp_snippets/content_suggestions_service.h
index 8b9c1eec7e2b94cf0205cc7490e4d2ee322bebea..a038fbfe830127433d161baf47b659f18e3f064e 100644
--- a/components/ntp_snippets/content_suggestions_service.h
+++ b/components/ntp_snippets/content_suggestions_service.h
@@ -212,9 +212,8 @@ class ContentSuggestionsService : public KeyedService,
   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);
 
@@ -251,11 +250,6 @@ class ContentSuggestionsService : public KeyedService,
   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>