Make GetDismissedSuggestionsForDebugging asynchronous

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 15 matching lines @@
 
 class NTPSnippetsService;
 
 // Retrieves suggestions from a number of ContentSuggestionsProviders and serves
 // them grouped into categories. There can be at most one provider per category.
 class ContentSuggestionsService : public KeyedService,
                                   public ContentSuggestionsProvider::Observer {
  public:
   using ImageFetchedCallback =
       base::Callback<void(const std::string& suggestion_id, const gfx::Image&)>;
+  using DismissedSuggestionsCallback = base::Callback<void(
+      Category category,
+      std::vector<ContentSuggestion> dismissed_suggestions)>;
 
   class Observer {
    public:
     // Fired every time the service receives a new set of data for the given
     // |category|, replacing any previously available data (though in most cases
     // there will be an overlap and only a few changes within the data). The new
     // data is then available through |GetSuggestionsForCategory(category)|.
     virtual void OnNewSuggestions(Category category) = 0;
 
     // Fired when the status of a suggestions category changed. When the status
@@ skipping 82 matching lines @@
   // stores in the service and the corresponding provider. It does, however, not
   // remove any suggestions from the provider's sources, so if its configuration
   // hasn't changed, it might return the same results when it fetches the next
   // time. In particular, calling this method will not mark any suggestions as
   // dismissed.
   void ClearCachedSuggestionsForDebugging(Category category);
 
   // Only for debugging use through the internals page.
   // Retrieves suggestions of the given |category| that have previously been
   // dismissed and are still stored in the respective provider. If the
-  // provider doesn't store dismissed suggestions, this returns an empty vector.
-  std::vector<ContentSuggestion> GetDismissedSuggestionsForDebugging(
-      Category category);
+  // provider doesn't store dismissed suggestions, the callback receives an
+  // empty vector. The callback may be called synchronously.
+  void GetDismissedSuggestionsForDebugging(
+      Category category,
+      const DismissedSuggestionsCallback& callback);
 
   // Only for debugging use through the internals page. Some providers
   // internally store a list of dismissed suggestions to prevent them from
   // reappearing. This function clears all suggestions of the given |category|
   // from such lists, making dismissed suggestions reappear (if the provider
   // supports it).
   void ClearDismissedSuggestionsForDebugging(Category category);
 
   CategoryFactory* category_factory() { return &category_factory_; }
 
@@ skipping 74 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_