Support action button to fetch more content suggestions

components/ntp_snippets/bookmarks/bookmark_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_BOOKMARKS_BOOKMARK_SUGGESTIONS_PROVIDER_H_
 #define COMPONENTS_NTP_SNIPPETS_BOOKMARKS_BOOKMARK_SUGGESTIONS_PROVIDER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 16 matching lines @@
   BookmarkSuggestionsProvider(ContentSuggestionsProvider::Observer* observer,
                               CategoryFactory* category_factory,
                               bookmarks::BookmarkModel* bookmark_model);
   ~BookmarkSuggestionsProvider() override;
 
  private:
   // ContentSuggestionsProvider implementation.
   std::vector<Category> GetProvidedCategories() override;
   CategoryStatus GetCategoryStatus(Category category) override;
   CategoryInfo GetCategoryInfo(Category category) override;
+  void FetchMoreSuggestions(Category category) override;
   void DismissSuggestion(const std::string& suggestion_id) override;
   void FetchSuggestionImage(const std::string& suggestion_id,
                             const ImageFetchedCallback& callback) override;
   void ClearCachedSuggestionsForDebugging(Category category) override;
   std::vector<ContentSuggestion> GetDismissedSuggestionsForDebugging(
       Category category) override;
   void ClearDismissedSuggestionsForDebugging(Category category) override;
 
   // bookmarks::BookmarkModelObserver implementation.
   void BookmarkModelLoaded(bookmarks::BookmarkModel* model,
@@ skipping 51 matching lines @@
 
   base::Time node_to_change_last_visit_date_;
   base::Time end_of_list_last_visit_date_;
 
   DISALLOW_COPY_AND_ASSIGN(BookmarkSuggestionsProvider);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_BOOKMARKS_BOOKMARK_SUGGESTIONS_PROVIDER_H_