Cache failover to LOAD_PREFERRING_CACHE if network response suggests offline.

net/http/http_transaction_unittest.h

Index: net/http/http_transaction_unittest.h
diff --git a/net/http/http_transaction_unittest.h b/net/http/http_transaction_unittest.h
index f1bd78ce124435f0fb7ade64db8bb52250842951..1e8869659b4081161ab1bad0fc7e8a3c70c38bc0 100644
--- a/net/http/http_transaction_unittest.h
+++ b/net/http/http_transaction_unittest.h
@@ -62,6 +62,9 @@ struct MockTransaction {
   int test_mode;
   MockTransactionHandler handler;
   net::CertStatus cert_status;
+  // Value returned by MockNetworkTransaction::Start (potentially
+  // asynchronously if |!(test_mode & TEST_MODE_SYNC_NET_START)|.)
+  net::Error return_code;
 };
 
 extern const MockTransaction kSimpleGET_Transaction;