[Remote suggestions] Move the throttler into the Scheduler

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 ef361fa61f7e90301d47ea82c47d97e5b672e4b4..4e3ec4d028dba500de5422c0d8118e9e962c96ea 100644
--- a/components/ntp_snippets/remote/remote_suggestions_provider.h
+++ b/components/ntp_snippets/remote/remote_suggestions_provider.h
@@ -32,6 +32,8 @@ 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;