Certificate Transparency: New component for obtaining fresh STHs.

net/cert/sth_observer.h

+// 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_CERT_STH_OBSERVER_H_
+#define NET_CERT_STH_OBSERVER_H_
+
+#include <set>
+
+#include "net/base/net_export.h"
+
+namespace net {
+
+namespace ct {
+
+struct SignedTreeHead;
+
+// Interface for receiving notifications of new STHs observed.
+class NET_EXPORT STHObserver {
+ public:
+  virtual ~STHObserver() {}
+
+  // Called with a new |sth| when one is observed.
+  // Expected to be called on the IO thread.
+  virtual void NewSTHObserved(const SignedTreeHead& sth) = 0;
+};
+
+// Interface for registering/unregistering observers.
+class NET_EXPORT STHReporter {

[Ryan Sleevi, 2016/04/06 18:32:51]

Shouldn't this be in its own header? STHDistributor exists to glue these two
classes together, which suggests that they're not intended to be coupled - if
they were, we could just couple them in a single class, right? I'm trying to
envision the flow of dependencies here, since the logical reason to separate
them out is to separate out dependencies / KISS (which is fantastic), but then
they end up coupled in the header.

[Eran Messeri, 2016/04/07 11:38:03]

You're right, I've separated them into different headers.

+ public:
+  virtual ~STHReporter() {}
+
+  virtual void RegisterObserver(STHObserver* observer) = 0;
+  virtual void UnregisterObserver(STHObserver* observer) = 0;
+};
+
+}  // namespace ct
+
+}  // namespace net
+
+#endif  // NET_CERT_STH_OBSERVER_H_