Adds a Fetch() method to the ContentSuggestionService which asks any provider to provide more conte…

chrome/browser/ntp_snippets/download_suggestions_provider.h

Index: chrome/browser/ntp_snippets/download_suggestions_provider.h
diff --git a/chrome/browser/ntp_snippets/download_suggestions_provider.h b/chrome/browser/ntp_snippets/download_suggestions_provider.h
index 7582c99aa6fd9477f621265fd8f91b682b374ddc..50d36f7e37d3c9720b06f8c7a9d06c58ee4378a4 100644
--- a/chrome/browser/ntp_snippets/download_suggestions_provider.h
+++ b/chrome/browser/ntp_snippets/download_suggestions_provider.h
@@ -61,6 +61,9 @@ class DownloadSuggestionsProvider
   void FetchSuggestionImage(
       const ntp_snippets::ContentSuggestion::ID& suggestion_id,
       const ImageFetchedCallback& callback) override;
+  void Fetch(const ntp_snippets::Category& category,
+             const std::set<std::string>& known_suggestion_ids,
+             FetchingCallback callback) override;
   void ClearHistory(
       base::Time begin,
       base::Time end,