Display DNS probe results.

chrome/browser/net/dns_probe_runner.h

+// Copyright (c) 2013 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 CHROME_BROWSER_NET_DNS_PROBE_RUNNER_H_
+#define CHROME_BROWSER_NET_DNS_PROBE_RUNNER_H_
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+
+namespace net {
+class DnsClient;
+class DnsResponse;
+class DnsTransaction;
+}
+
+namespace chrome_browser_net {
+
+// Runs DNS probes using a single DnsClient and evaluates the responses.
+// (Currently requests A records for google.com and expects at least one IP
+// address in the response.)
+// Used by DnsProbeService to probe the system and public DNS configurations.
+class DnsProbeRunner {
+ public:
+  enum Result {
+    UNKNOWN,

[mmenke, 2013/06/26 15:48:20]

I think it's worth adding a note that these are used in histograms.  So it's not
safe to remove entries, and new entries much be added to the bottom.  Otherwise,
I'd suggest removing UNKNOWN.

[Deprecated (see juliatuttle), 2013/06/26 22:23:56]

Done.

+    CORRECT,     // Response contains at least one A record.
+    INCORRECT,   // Response claimed success but included no A records.
+    FAILING,     // Response included an error or was malformed.
+    UNREACHABLE  // No response received (timeout, network unreachable, etc.).
+  };
+
+  DnsProbeRunner();
+  ~DnsProbeRunner();
+
+  // Starts a probe using the client specified with SetClient, which must have
+  // been called before RunProbe.  |callback| will be called asynchronously
+  // when the result is ready (even if it is ready synchronously).  Must not
+  // be called again until the callback is called (but may be called during the
+  // callback).

[mmenke, 2013/06/26 15:48:20]

Instead of all the parentheses, use commas before the remarks, as both are
basically just compound sentences.

[Deprecated (see juliatuttle), 2013/06/26 22:23:56]

Done.

+  void RunProbe(const base::Closure& callback);
+
+  // Sets the DnsClient that will be used for DNS probes sent by this runner.
+  // Must be called before RunProbe; can be called repeatedly, including during
+  // a probe.  (It will not, of course, affect the in-flight probe.)

[mmenke, 2013/06/26 15:48:20]

Parenthesis not needed.  Also suggest removing the "of course" - it's not
actually self-evident that it doesn't affect the in-flight probe.

[Deprecated (see juliatuttle), 2013/06/26 22:23:56]

Done.

+  void SetClient(scoped_ptr<net::DnsClient> client);
+
+  // Returns true if a probe is running.  Guaranteed to return true after
+  // RunProbe returns, and false during and after the callback.
+  bool IsRunning() const;
+
+  // Returns the result of the last probe.
+  Result result() const { return result_; }
+
+ private:
+  void OnTransactionComplete(net::DnsTransaction* transaction,
+                             int net_error,
+                             const net::DnsResponse* response);
+  void CallCallback();
+
+  base::WeakPtrFactory<DnsProbeRunner> weak_factory_;
+  scoped_ptr<net::DnsClient> client_;
+  base::Closure callback_;
+  scoped_ptr<net::DnsTransaction> transaction_;
+  Result result_;
+
+  DISALLOW_COPY_AND_ASSIGN(DnsProbeRunner);
+};
+
+}  // namespace chrome_browser_net
+
+#endif  // CHROME_BROWSER_NET_DNS_PROBE_RUNNER_H_