Use bookmark creation date fallback for 6 weeks after installing M54

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>
 
 #include "components/bookmarks/browser/bookmark_model_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/ntp_snippets/category.h"
 #include "components/ntp_snippets/category_status.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
 
+class PrefRegistrySimple;
+class PrefService;
+
 namespace gfx {
 class Image;
 }
 
 namespace ntp_snippets {
 
 // Provides content suggestions from the bookmarks model.
 class BookmarkSuggestionsProvider : public ContentSuggestionsProvider,
                                     public bookmarks::BookmarkModelObserver {
  public:
   BookmarkSuggestionsProvider(ContentSuggestionsProvider::Observer* observer,
                               CategoryFactory* category_factory,
-                              bookmarks::BookmarkModel* bookmark_model);
+                              bookmarks::BookmarkModel* bookmark_model,
+                              PrefService* pref_service);
   ~BookmarkSuggestionsProvider() override;
 
+  static void RegisterProfilePrefs(PrefRegistrySimple* registry);
+
  private:
   // ContentSuggestionsProvider implementation.
   std::vector<Category> GetProvidedCategories() override;
   CategoryStatus GetCategoryStatus(Category category) override;
   CategoryInfo GetCategoryInfo(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(
@@ skipping 50 matching lines @@
   void NotifyStatusChanged(CategoryStatus new_status);
 
   CategoryStatus category_status_;
   const Category provided_category_;
   bookmarks::BookmarkModel* bookmark_model_;
   bool fetch_requested_;
 
   base::Time node_to_change_last_visit_date_;
   base::Time end_of_list_last_visit_date_;
 
+  // TODO(jkrcal): Remove this field and the pref after M55.
+  // For six weeks after first installing M54, this is true and the
+  // fallback implemented in BookmarkLastVisitUtils is activated.
+  bool creation_date_fallback_;
+
   DISALLOW_COPY_AND_ASSIGN(BookmarkSuggestionsProvider);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_BOOKMARKS_BOOKMARK_SUGGESTIONS_PROVIDER_H_