Implement offline mode behind a flag

net/http/http_cache_transaction.cc

Index: net/http/http_cache_transaction.cc
diff --git a/net/http/http_cache_transaction.cc b/net/http/http_cache_transaction.cc
index 491f2f39345013eeb2508d8b30942fc3cbabb2d9..ac22d176f0ee320555d677c8bf726a0c370dee49 100644
--- a/net/http/http_cache_transaction.cc
+++ b/net/http/http_cache_transaction.cc
@@ -884,6 +884,7 @@ int HttpCache::Transaction::DoSuccessfulSendRequest() {
     next_state_ = STATE_SEND_REQUEST;
     return OK;
   }
+
   if (handling_206_ && mode_ == READ_WRITE && !truncated_ && !is_sparse_) {
     // We have stored the full entry, but it changed and the server is
     // sending a range. We have to delete the old entry.
@@ -1212,6 +1213,7 @@ int HttpCache::Transaction::DoUpdateCachedResponse() {
   response_.headers->Update(*new_response_->headers);
   response_.response_time = new_response_->response_time;
   response_.request_time = new_response_->request_time;
+  response_.network_accessed = new_response_->network_accessed;
 
   if (response_.headers->HasHeaderValue("cache-control", "no-store")) {
     if (!entry_->doomed) {