Support action button to fetch more content suggestions

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 70 matching lines @@
 
   // Gets the meta information of a category.
   base::Optional<CategoryInfo> GetCategoryInfo(Category category) const;
 
   // Gets the available suggestions for a category. The result is empty if the
   // category is available and empty, but also if the category is unavailable
   // for any reason, see |GetCategoryStatus()|.
   const std::vector<ContentSuggestion>& GetSuggestionsForCategory(
       Category category) const;
 
+  // Triggers a fetch for new suggestions (over the network, for example) for
+  // the given |category|. This must be initiated by the user (e.g. by clicking
+  // the a "More" button).

[Marc Treib, 2016/08/10 09:40:31]

nit: remove "a"

[Philipp Keck, 2016/08/10 13:14:47]

Done.

+  void FetchMoreSuggestions(Category category);
+
   // Fetches the image for the suggestion with the given |suggestion_id| and
   // runs the |callback|. If that suggestion doesn't exist or the fetch fails,
   // the callback gets an empty image. The callback will not be called
   // synchronously.
   void FetchSuggestionImage(const std::string& suggestion_id,
                             const ImageFetchedCallback& callback);
 
   // Dismisses the suggestion with the given |suggestion_id|, if it exists.
   // This will not trigger an update through the observers.
   void DismissSuggestion(const std::string& suggestion_id);
@@ skipping 111 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_