Restrict transmission of external exp ids to signed in users.

components/autofill/core/browser/autofill_download_manager.cc

Index: components/autofill/core/browser/autofill_download_manager.cc
diff --git a/components/autofill/core/browser/autofill_download_manager.cc b/components/autofill/core/browser/autofill_download_manager.cc
index 021a85024ea5a8908a029ff7fe1775f99860e926..331de9984500330b84b5a68b287e47b68a6b502d 100644
--- a/components/autofill/core/browser/autofill_download_manager.cc
+++ b/components/autofill/core/browser/autofill_download_manager.cc
@@ -247,8 +247,12 @@ bool AutofillDownloadManager::StartRequest(
                         net::LOAD_DO_NOT_SEND_COOKIES);
   // Add Chrome experiment state to the request headers.
   net::HttpRequestHeaders headers;
-  variations::AppendVariationHeaders(
-      fetcher->GetOriginalURL(), driver_->IsOffTheRecord(), false, &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.
+  bool is_signed_in = false;
+  variations::AppendVariationHeaders(fetcher->GetOriginalURL(),
+                                     driver_->IsOffTheRecord(), false,
+                                     is_signed_in, &headers);
   fetcher->SetExtraRequestHeaders(headers.ToString());
   fetcher->Start();