Remove deleted offline page suggestions from opened NTPs

components/ntp_snippets/content_suggestions_service.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_CONTENT_SUGGESTIONS_SERVICE_H_
 #define COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 32 matching lines @@
     virtual void OnNewSuggestions(Category category) = 0;
 
     // Fired when the status of a suggestions category changed. When the status
     // changes to an unavailable status, the suggestions of the respective
     // category have been invalidated, which means that they must no longer be
     // displayed to the user. The UI must immediately clear any suggestions of
     // that category.
     virtual void OnCategoryStatusChanged(Category category,
                                          CategoryStatus new_status) = 0;
 
+    // Fired when a suggestion has been invalidated. The UI must immediately
+    // clear the suggestion even from open NTPs. Invalidation happens, for
+    // example, when the content that the suggestion refers to is gone.
+    // Note that this event may be fired even if the corresponding |category| is
+    // not currently AVAILABLE, because open UIs may still be showing the
+    // suggestion that is to be removed. This event may also be fired for
+    // |suggestion_id|s that never existed and should be ignored in that case.
+    virtual void OnSuggestionInvalidated(Category category,
+                                         const std::string& suggestion_id) = 0;
+
     // Sent when the service is shutting down. After the service has shut down,
     // it will not provide any data anymore, though calling the getters is still
     // safe.
     virtual void ContentSuggestionsServiceShutdown() = 0;
 
    protected:
     virtual ~Observer() {}
   };
 
   enum State {
@@ skipping 85 matching lines @@
  private:
   friend class ContentSuggestionsServiceTest;
 
   // Implementation of ContentSuggestionsProvider::Observer.
   void OnNewSuggestions(ContentSuggestionsProvider* provider,
                         Category category,
                         std::vector<ContentSuggestion> suggestions) override;
   void OnCategoryStatusChanged(ContentSuggestionsProvider* provider,
                                Category category,
                                CategoryStatus new_status) override;
+  void OnSuggestionInvalidated(ContentSuggestionsProvider* provider,
+                               Category category,
+                               const std::string& suggestion_id) override;
 
   // Registers the given |provider| for the given |category|, unless it is
   // already registered. Returns true if the category was newly registered or
   // false if it was present before.
   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.
+  bool RemoveSuggestionByID(Category category,
+                            const std::string& suggestion_id);
+
   // Fires the OnCategoryStatusChanged event for the given |category|.
   void NotifyCategoryStatusChanged(Category category);
 
   // Whether the content suggestions feature is enabled.
   State state_;
 
   // Provides new and existing categories and an order for them.
   CategoryFactory category_factory_;
 
   // All registered providers, owned by the service.
@@ skipping 31 matching lines @@
   // background fetching and debugging calls to it. If the NTPSnippetsService is
   // loaded, it is also present in |providers_|, otherwise this is a nullptr.
   NTPSnippetsService* ntp_snippets_service_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentSuggestionsService);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_