Update some comments about variations headers API use.

components/suggestions/suggestions_service_impl.cc

Index: components/suggestions/suggestions_service_impl.cc
diff --git a/components/suggestions/suggestions_service_impl.cc b/components/suggestions/suggestions_service_impl.cc
index f181599c6676b05f116bf142b2a409fff6a98ef0..5f30527c68bed1804c66139fcf5e696ebfa879bf 100644
--- a/components/suggestions/suggestions_service_impl.cc
+++ b/components/suggestions/suggestions_service_impl.cc
@@ -423,8 +423,8 @@ SuggestionsServiceImpl::CreateSuggestionsRequest(
   request->SetRequestContext(url_request_context_);
   // Add Chrome experiment state to the request headers.
   net::HttpRequestHeaders headers;
-  // Note: It's fine to pass in |is_signed_in| false, which does not affect
-  // transmission of experiment ids coming from the variations server.
+  // Note: It's OK to pass |is_signed_in| false if it's unknown, as it does
+  // not affect transmission of experiments coming from the variations server.
   bool is_signed_in = false;
   variations::AppendVariationHeaders(request->GetOriginalURL(), false, false,
                                      is_signed_in, &headers);