FetchMore functionality backend

components/ntp_snippets/content_suggestions_service.h

Index: components/ntp_snippets/content_suggestions_service.h
diff --git a/components/ntp_snippets/content_suggestions_service.h b/components/ntp_snippets/content_suggestions_service.h
index be34e7290c43a0f9f3db422e13111c16b0fee6c6..9ef6ea7d8b7f87efaba655bb5131b8a51c412771 100644
--- a/components/ntp_snippets/content_suggestions_service.h
+++ b/components/ntp_snippets/content_suggestions_service.h
@@ -34,6 +34,7 @@ class Image;
 namespace ntp_snippets {
 
 class NTPSnippetsService;
+class NTPSnippetsFetcher;

[Marc Treib, 2016/10/20 16:51:39]

Not needed I think?

[Marc Treib, 2016/10/28 14:49:49]

Done.

 
 // Retrieves suggestions from a number of ContentSuggestionsProviders and serves
 // them grouped into categories. There can be at most one provider per category.
@@ -44,6 +45,8 @@ class ContentSuggestionsService : public KeyedService,
   using ImageFetchedCallback = base::Callback<void(const gfx::Image&)>;
   using DismissedSuggestionsCallback = base::Callback<void(
       std::vector<ContentSuggestion> dismissed_suggestions)>;
+  using FetchedMoreCallback =
+      base::Callback<void(std::vector<ContentSuggestion> suggestions)>;
 
   class Observer {
    public:
@@ -135,6 +138,11 @@ class ContentSuggestionsService : public KeyedService,
   // Returns whether |category| is dismissed.
   bool IsCategoryDismissed(Category category) const;
 
+  // Fetches additional contents for the given |category|. If the fetch was
+  // completed, the given |callback| is called with the updated content.
+  // This includes new and old data.
+  void FetchMore(const Category& category, FetchedMoreCallback callback);

[Marc Treib, 2016/10/20 16:51:39]

const&

[Marc Treib, 2016/10/28 14:49:49]

Done.

+
   // Observer accessors.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);