stale-while-revalidate experimental implementation.

Simplistic implementation of stale-while-revalidate. See design doc at
https://docs.google.com/document/d/1DMCIMAKjyKeYiu69jlI5OsO2pGyAMb81XflYK4hxsNM/edit?usp=sharing

This implementation has known flaws:
1. Set-Cookie, Strict-Transport-Security and Public-Key-Pins headers
are lost from the responses of asynchronous revalidations.
2. Conditional requests sent from the Blink cache do not have the
stale-while-revalidate logic applied to them.
3. Support for the bandwidth reduction proxy is hacky.

It will be replaced with a better implementation if/when the concept is proven.

BUG=348877
TEST=net_unittests

Review URL: https://codereview.chromium.org/455623003

Cr-Commit-Position: refs/heads/master@{#298649}

1 files changed, 7 insertions, 2 deletions

diff --git a/net/http/http_transaction_test_util.cc b/net/http/http_transaction_test_util.cc
index 7d031d8..dbbca6c 100644
--- a/net/http/http_transaction_test_util.cc
+++ b/net/http/http_transaction_test_util.cc
@@ -277,8 +277,13 @@ bool MockNetworkTransaction::IsReadyToRestartForAuth() {
   if (!request_)
     return false;
 
-  // Only mock auth when the test asks for it.
-  return request_->extra_headers.HasHeader("X-Require-Mock-Auth");
+  if (!request_->extra_headers.HasHeader("X-Require-Mock-Auth"))
+    return false;
+
+  // Allow the mock server to decide whether authentication is required or not.
+  std::string status_line = response_.headers->GetStatusLine();
+  return status_line.find(" 401 ") != std::string::npos ||
+      status_line.find(" 407 ") != std::string::npos;
 }
 
 int MockNetworkTransaction::Read(net::IOBuffer* buf, int buf_len,