Update some comments about variations headers API use.

components/feedback/feedback_uploader_chrome.cc

Index: components/feedback/feedback_uploader_chrome.cc
diff --git a/components/feedback/feedback_uploader_chrome.cc b/components/feedback/feedback_uploader_chrome.cc
index 9b3cb82e9cf0212c9bb987e977bcf5b1cdd5c683..0b18305d920b12584508bebbf8cb9d4b63cfb666 100644
--- a/components/feedback/feedback_uploader_chrome.cc
+++ b/components/feedback/feedback_uploader_chrome.cc
@@ -60,8 +60,8 @@ void FeedbackUploaderChrome::DispatchReport(const std::string& data) {
       fetcher, data_use_measurement::DataUseUserData::FEEDBACK_UPLOADER);
   // Tell feedback server about the variation state of this install.
   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(),
                                      context_->IsOffTheRecord(), false,