[NTP::PhysicalWeb] Implement suggestion dismissal.

components/ntp_snippets/physical_web_pages/physical_web_page_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_PHYSICAL_WEB_PAGES_PHYSICAL_WEB_PAGE_SUGGESTIONS_PROVIDER_H_
 #define COMPONENTS_NTP_SNIPPETS_PHYSICAL_WEB_PAGES_PHYSICAL_WEB_PAGE_SUGGESTIONS_PROVIDER_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/values.h"
 #include "components/ntp_snippets/category.h"
 #include "components/ntp_snippets/category_factory.h"
 #include "components/ntp_snippets/category_status.h"
 #include "components/ntp_snippets/content_suggestion.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
 #include "components/physical_web/data_source/physical_web_data_source.h"
 #include "components/physical_web/data_source/physical_web_listener.h"
 
+class PrefRegistrySimple;
+class PrefService;
+
 namespace ntp_snippets {
 
 // Provides content suggestions from the Physical Web Service.
 class PhysicalWebPageSuggestionsProvider
     : public ContentSuggestionsProvider,
       public physical_web::PhysicalWebListener {
  public:
   PhysicalWebPageSuggestionsProvider(
       ContentSuggestionsProvider::Observer* observer,
       CategoryFactory* category_factory,
-      physical_web::PhysicalWebDataSource* physical_web_data_source);
+      physical_web::PhysicalWebDataSource* physical_web_data_source,
+      PrefService* pref_service);
   ~PhysicalWebPageSuggestionsProvider() override;
 
   // ContentSuggestionsProvider implementation.
   CategoryStatus GetCategoryStatus(Category category) override;
   CategoryInfo GetCategoryInfo(Category category) override;
   void DismissSuggestion(const ContentSuggestion::ID& suggestion_id) override;
   void FetchSuggestionImage(const ContentSuggestion::ID& suggestion_id,
                             const ImageFetchedCallback& callback) override;
   void Fetch(const Category& category,
              const std::set<std::string>& known_suggestion_ids,
              const FetchDoneCallback& callback) override;
   void ClearHistory(
       base::Time begin,
       base::Time end,
       const base::Callback<bool(const GURL& url)>& filter) override;
   void ClearCachedSuggestions(Category category) override;
   void GetDismissedSuggestionsForDebugging(
       Category category,
       const DismissedSuggestionsCallback& callback) override;
   void ClearDismissedSuggestionsForDebugging(Category category) override;
 
+  static void RegisterProfilePrefs(PrefRegistrySimple* registry);
+
  private:
   friend class PhysicalWebPageSuggestionsProviderTest;
 
   // Updates the |category_status_| and notifies the |observer_|, if necessary.
   void NotifyStatusChanged(CategoryStatus new_status);
 
   // Manually requests all physical web pages and updates the suggestions.
   void FetchPhysicalWebPages();
 
   // Returns at most |max_count| ContentSuggestions with IDs not in
-  // |excluded_ids| and sorted by distance (the closest first). The raw pages
-  // are obtained from Physical Web data source.
+  // |excluded_ids| and sorted by distance (the closest first). Dismissed
+  // suggestions are excluded automatically (no need to add them to
+  // |excluded_ids|) and pruned. The raw pages are obtained from Physical Web
+  // data source.
   std::vector<ContentSuggestion> GetMostRecentPhysicalWebPagesWithFilter(
       int max_count,
       const std::set<std::string>& excluded_ids);
 
   // Converts an Physical Web page to a ContentSuggestion.
   ContentSuggestion ConvertPhysicalWebPage(
       const base::DictionaryValue& page) const;
 
   // PhysicalWebListener implementation.
   void OnFound(const std::string& url) override;
   void OnLost(const std::string& url) override;
   void OnDistanceChanged(const std::string& url,
                          double distance_estimate) override;
 
+  // Fires the |OnSuggestionInvalidated| event for the suggestion corresponding
+  // to the given |page_id| and deletes it from the dismissed IDs list, if
+  // necessary.
+  void InvalidateSuggestion(const std::string& page_id);
+
+  // Reads dismissed IDs from Prefs.
+  std::set<std::string> ReadDismissedIDsFromPrefs() const;
+
+  // Writes |dismissed_ids| into Prefs.
+  void StoreDismissedIDsToPrefs(const std::set<std::string>& dismissed_ids);
+
   CategoryStatus category_status_;
   const Category provided_category_;
   physical_web::PhysicalWebDataSource* physical_web_data_source_;
+  PrefService* pref_service_;
 
   DISALLOW_COPY_AND_ASSIGN(PhysicalWebPageSuggestionsProvider);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_PHYSICAL_WEB_PAGES_PHYSICAL_WEB_PAGE_SUGGESTIONS_PROVIDER_H_