[Remote suggestions] Remove the unique_ptr wrapper around callbacks

components/ntp_snippets/remote/remote_suggestions_provider.h

Index: components/ntp_snippets/remote/remote_suggestions_provider.h
diff --git a/components/ntp_snippets/remote/remote_suggestions_provider.h b/components/ntp_snippets/remote/remote_suggestions_provider.h
index 4e3ec4d028dba500de5422c0d8118e9e962c96ea..8a6e4f89a36836058079e5bbe17027d9ed42e660 100644
--- a/components/ntp_snippets/remote/remote_suggestions_provider.h
+++ b/components/ntp_snippets/remote/remote_suggestions_provider.h
@@ -32,10 +32,7 @@ class RemoteSuggestionsProvider : public ContentSuggestionsProvider {
   // triggered by the user and have lower priority on the server. After the
   // fetch finished, the provided |callback| will be triggered with the status
   // of the fetch (unless nullptr).
-  // TODO(jkrcal): Change to FetchStatusCallback callback as callbacks already
-  // have is_empty() functionality. crbug.com/676317
-  virtual void RefetchInTheBackground(
-      std::unique_ptr<FetchStatusCallback> callback) = 0;
+  virtual void RefetchInTheBackground(const FetchStatusCallback& callback) = 0;
 
   virtual const RemoteSuggestionsFetcher* suggestions_fetcher_for_debugging()
       const = 0;