[Offline Pages] Set up the initial prefetching service.

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 <set>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/observer_list.h"
 #include "base/optional.h"
 #include "base/scoped_observer.h"
+#include "base/supports_user_data.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/time/time.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/history_service_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/ntp_snippets/callbacks.h"
 #include "components/ntp_snippets/category.h"
 #include "components/ntp_snippets/category_rankers/category_ranker.h"
 #include "components/ntp_snippets/category_status.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
@@ skipping 12 matching lines @@
 struct LargeIconImageResult;
 }  // namespace favicon_base
 
 namespace ntp_snippets {
 
 class RemoteSuggestionsProvider;
 
 // 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 base::SupportsUserData,
                                   public ContentSuggestionsProvider::Observer,
                                   public SigninManagerBase::Observer,
                                   public history::HistoryServiceObserver {
  public:
   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)|.
@@ skipping 348 matching lines @@
 
   // Provides order for categories.
   std::unique_ptr<CategoryRanker> category_ranker_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentSuggestionsService);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_