Add enterprise policy to exempt hosts from Certificate Transparency

components/certificate_transparency/ct_policy_manager.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 COMPONENTS_CERTIFICATE_TRANSPARENCY_CT_POLICY_MANAGER_H_
+#define COMPONENTS_CERTIFICATE_TRANSPARENCY_CT_POLICY_MANAGER_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "components/prefs/pref_change_registrar.h"
+#include "net/http/transport_security_state.h"
+
+namespace base {
+class SequencedTaskRunner;

[mmenke, 2016/06/27 22:11:57]

Should this be included explicitly?  Seems like CTPolicyManager's prototype
requires we know about its increment method, though I'm honestly not sure.

[Ryan Sleevi, 2016/06/27 22:49:19]

It doesn't need to be (only at call-site; you can actually pass through the
objects if you have something that returns a scoped_refptr<> because of RVO)

+}  // base
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}  // user_prefs
+
+namespace certificate_transparency {
+
+class CTPolicyManager {

[mmenke, 2016/06/27 22:11:57]

Should document this class, and its lifetime and threading expectations.  Fine
to create on one thread, destroy on another, I assume?

[Ryan Sleevi, 2016/06/27 22:49:19]

Yeah; it's created on UI, shut down on UI, deleted on IO AIUI - does that match?

+ public:
+  // Registers the preferences related to Certificate Transparency policy
+  // in the given pref registry.
+  static void RegisterPrefs(user_prefs::PrefRegistrySyncable* registry);
+
+  explicit CTPolicyManager(

[mmenke, 2016/06/27 22:11:57]

nit:  Explicit not needed.

+      PrefService* pref_service,
+      scoped_refptr<base::SequencedTaskRunner> network_task_runner);
+  ~CTPolicyManager();
+
+  void Shutdown();

[mmenke, 2016/06/27 22:11:56]

As used in ProfileIOData, its delegate on the UIThread is used after Shutdown is
called...  If that's fine, should say so.

[Ryan Sleevi, 2016/06/27 22:49:19]

I'm perhaps not sure I understood your comment.

I think you're saying it should be clearer that:
1) Shutdown is called on the UI thread
2) the RequireCTDelegate from GetDelegate() is safe to be used after Shutdown,
but it doesn't receive any more updates

Is that correct?

[mmenke, 2016/06/28 12:38:00]

Right, I just wanted enough usage comments here that it can be verified
ProfileIOData's use of this class is correct, without delving into the
implementation of the class (It's not complicated, but API docs should be
sufficient to use a class correctly).

The comments you added look to cover this (I consider reviewing your interface
docs here part of reviewing the ProfileIOData changes, since their correctness
depends on them).

+
+  // Gets the RequireCTDelegate() that responds based on the policies set
+  // via the pref service. This object MUST only be used on the network
+  // task runner provided, and MUST NOT be used after this object has
+  // been destructed.
+  net::TransportSecurityState::RequireCTDelegate* GetDelegate();
+
+ private:
+  class CTDelegate;
+
+  // Schedules an update of the CTPolicyDelegate. As it's possible that
+  // multiple preferences may be updated at the same time, this exists to
+  // schedule only a single update.
+  void ScheduleUpdate();
+
+  // Performs the actual update of the CTPolicyDelegate once preference
+  // changes have quiesced.
+  void Update();
+
+  PrefChangeRegistrar pref_change_registrar_;
+  std::unique_ptr<CTDelegate> delegate_;
+
+  base::WeakPtrFactory<CTPolicyManager> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CTPolicyManager);
+};
+
+}  // namespace certificate_transparency
+
+#endif  // COMPONENTS_CERTIFICATE_TRANSPARENCY_CT_POLICY_MANAGER_H_