Restrict transmission of external exp ids to signed in users.

chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc

Index: chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
diff --git a/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
index e6faf04a613b0ab023640207e96eb15c066b3f74..5d8a440a6d2b35f077db4d2a7db5981a2e1f8aa4 100644
--- a/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
@@ -480,8 +480,11 @@ void ChromeResourceDispatcherHostDelegate::RequestBeginning(
     net::HttpRequestHeaders headers;
     headers.CopyFrom(request->extra_request_headers());
     bool is_off_the_record = io_data->IsOffTheRecord();
+    bool is_signed_in =
+        !is_off_the_record &&
+        !io_data->google_services_account_id()->GetValue().empty();
     variations::AppendVariationHeaders(
-        request->url(), is_off_the_record,
+        request->url(), is_off_the_record, is_signed_in,
         !is_off_the_record && io_data->GetMetricsEnabledStateOnIOThread(),
         &headers);
     request->SetExtraRequestHeaders(headers);