Record the number of freshness periods since a stale HttpCache entry was last used

net/http/http_cache_transaction.h

Index: net/http/http_cache_transaction.h
diff --git a/net/http/http_cache_transaction.h b/net/http/http_cache_transaction.h
index 8e26337820396e3fd9f1825012df736f2c159dcd..06f9bbfb4fa51ae3ee06339639667120e6cc2b2b 100644
--- a/net/http/http_cache_transaction.h
+++ b/net/http/http_cache_transaction.h
@@ -484,6 +484,8 @@ class HttpCache::Transaction : public HttpTransaction {
   base::TimeTicks entry_lock_waiting_since_;
   base::TimeTicks first_cache_access_since_;
   base::TimeTicks send_request_since_;
+  base::Time open_entry_last_used_;
+  base::TimeDelta stale_entry_freshness_;
 
   int64_t total_received_bytes_;
   int64_t total_sent_bytes_;