Cache failover to LOAD_PREFERRING_CACHE if network response suggests offline.

net/http/http_response_info.h

Index: net/http/http_response_info.h
diff --git a/net/http/http_response_info.h b/net/http/http_response_info.h
index f5f1c2425d9250007a7237689110e6bace033d5c..65204f4e47e3c124b7225ea0bb5f5077d130c9d1 100644
--- a/net/http/http_response_info.h
+++ b/net/http/http_response_info.h
@@ -48,6 +48,11 @@ class NET_EXPORT HttpResponseInfo {
   // when reloading previously visited pages (without going over the network).
   bool was_cached;
 
+  // True if the request was fetched from cache rather than the network
+  // because of a LOAD_FROM_CACHE_IF_OFFLINE flag when the system
+  // was unable to contact the server.
+  bool server_data_unavailable;
+
   // True if the request was fetched over a SPDY channel.
   bool was_fetched_via_spdy;