Cronet: Use stale DNS cache entries experimentally.

net/dns/stale_host_resolver.h

Index: net/dns/stale_host_resolver.h
diff --git a/net/dns/stale_host_resolver.h b/net/dns/stale_host_resolver.h
new file mode 100644
index 0000000000000000000000000000000000000000..d9b8810b58e8b95a449f3f18681b3f8044180df5
--- /dev/null
+++ b/net/dns/stale_host_resolver.h
@@ -0,0 +1,56 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_DNS_STALE_HOST_RESOLVER_H_
+#define NET_DNS_STALE_HOST_RESOLVER_H_
+
+#include "net/dns/host_resolver.h"
+
+namespace net {
+
+class NET_EXPORT StaleHostResolver : public HostResolver {

[Ryan Sleevi, 2016/04/26 02:25:36]

Document (throughout this file; methods & class)

[Julia Tuttle, 2016/04/27 14:50:26]

Done.

+ public:
+  struct NET_EXPORT StaleOptions {
+    base::TimeDelta delay;
+    base::TimeDelta max_expired_time;
+    bool allow_other_network;
+    unsigned max_stale_uses;
+  };
+
+  StaleHostResolver(std::unique_ptr<HostResolver> inner_resolver,
+                    const StaleOptions& stale_options);
+
+  ~StaleHostResolver() override;
+
+  int Resolve(const RequestInfo& info,
+              RequestPriority priority,
+              AddressList* addresses,
+              const CompletionCallback& callback,
+              RequestHandle* out_req,
+              const BoundNetLog& net_log) override;
+
+  void CancelRequest(RequestHandle req) override;
+
+  // Pass through to the inner resolver:
+  int ResolveFromCache(const RequestInfo& info,
+                       AddressList* addresses,
+                       const BoundNetLog& net_log) override;
+  int ResolveStaleFromCache(const RequestInfo& info,
+                            AddressList* addresses,
+                            HostCache::StaleEntryInfo* stale_info,
+                            const BoundNetLog& net_log) override;
+  void SetDnsClientEnabled(bool enabled) override;
+  HostCache* GetHostCache() override;
+  std::unique_ptr<base::Value> GetDnsConfigAsValue() const override;
+
+ private:
+  class Request;
+
+  std::unique_ptr<HostResolver> resolver_;
+  StaleOptions options_;
+};
+
+}  // namespace net
+
+#endif  // NET_DNS_STALE_HOST_RESOLVER_H_