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 and the pref when it's not needed anymore.

[Marc Treib, 2016/08/19 11:41:12]

s/when it's not needed anymore/after M55/
Be as specific as possible with this kind of TODO. Chances are the details will
get forgotten, and at some point in the far future someone will wonder if this
thing is still needed.

[Philipp Keck, 2016/08/19 12:49:52]

Done.

+  // 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_