Update some comments about variations headers API use.

components/omnibox/browser/zero_suggest_provider.cc

Index: components/omnibox/browser/zero_suggest_provider.cc
diff --git a/components/omnibox/browser/zero_suggest_provider.cc b/components/omnibox/browser/zero_suggest_provider.cc
index 652034f17f239585321703a38d3155ccac9ddf7c..b3baac699b5d49d90287475a0a26e6fc133dec70 100644
--- a/components/omnibox/browser/zero_suggest_provider.cc
+++ b/components/omnibox/browser/zero_suggest_provider.cc
@@ -333,8 +333,8 @@ void ZeroSuggestProvider::Run(const GURL& suggest_url) {
     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,