Update some comments about variations headers API use.

components/omnibox/browser/search_provider.cc

Index: components/omnibox/browser/search_provider.cc
diff --git a/components/omnibox/browser/search_provider.cc b/components/omnibox/browser/search_provider.cc
index 55e363fc8d811a303f88ccf36b1a6bd0c3932c74..113ed9ea6d72c7c531b25f61578c858e4a0427df 100644
--- a/components/omnibox/browser/search_provider.cc
+++ b/components/omnibox/browser/search_provider.cc
@@ -890,8 +890,8 @@ std::unique_ptr<net::URLFetcher> SearchProvider::CreateSuggestFetcher(
   fetcher->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES);
   // 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(fetcher->GetOriginalURL(),
                                      client()->IsOffTheRecord(), false,