Restrict transmission of external exp ids to signed in users.

components/suggestions/suggestions_service.cc

Index: components/suggestions/suggestions_service.cc
diff --git a/components/suggestions/suggestions_service.cc b/components/suggestions/suggestions_service.cc
index 16fe605c213fd7e814845910e94fea0515528a0e..b5850f0da8c13282cc659c43d1d921d1cb7ba98d 100644
--- a/components/suggestions/suggestions_service.cc
+++ b/components/suggestions/suggestions_service.cc
@@ -423,8 +423,11 @@ std::unique_ptr<net::URLFetcher> SuggestionsService::CreateSuggestionsRequest(
   request->SetRequestContext(url_request_context_);
   // 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.
+  bool is_signed_in = false;
   variations::AppendVariationHeaders(request->GetOriginalURL(), false, false,
-                                     &headers);
+                                     is_signed_in, &headers);
   request->SetExtraRequestHeaders(headers.ToString());
   if (!access_token.empty()) {
     request->AddExtraRequestHeader(