[Content suggestions] Add a function to the service API to fetch favicons

components/ntp_snippets/content_suggestions_service.cc

Index: components/ntp_snippets/content_suggestions_service.cc
diff --git a/components/ntp_snippets/content_suggestions_service.cc b/components/ntp_snippets/content_suggestions_service.cc
index 3e274ff22a9ba03b263f0d5f716718e721ebb9fa..92d8cd783ec75271ccaa691dce9c573d80df9847 100644
--- a/components/ntp_snippets/content_suggestions_service.cc
+++ b/components/ntp_snippets/content_suggestions_service.cc
@@ -125,6 +125,14 @@ void ContentSuggestionsService::FetchSuggestionImage(
       suggestion_id, callback);
 }
 
+void ContentSuggestionsService::FetchSuggestionFavicon(
+    const ContentSuggestion::ID& suggestion_id,
+    int minimum_size_in_pixel,
+    int desired_size_in_pixel,
+    const ImageFetchedCallback& callback) {
+  // TODO(jkrcal): Implement.
+}
+
 void ContentSuggestionsService::ClearHistory(
     base::Time begin,
     base::Time end,