Refactor FileBasedPolicyProvider, introduce AsynchronousPolicyProvider.

chrome/browser/policy/asynchronous_policy_loader.h

+// Copyright (c) 2010 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_POLICY_ASYNCHRONOUS_POLICY_LOADER_H_
+#define CHROME_BROWSER_POLICY_ASYNCHRONOUS_POLICY_LOADER_H_
+#pragma once
+
+#include "base/ref_counted.h"
+#include "base/values.h"
+#include "chrome/browser/policy/asynchronous_policy_provider.h"
+
+namespace policy {
+
+class ConfigurationPolicyProvider;
+
+class AsynchronousPolicyLoader
+    : public base::RefCountedThreadSafe<AsynchronousPolicyLoader> {
+ public:
+  AsynchronousPolicyLoader(
+      base::WeakPtr<ConfigurationPolicyProvider> provider,

[Mattias Nissler (ping if slow), 2010/12/02 18:16:00]

I thought the idea was to change the notification interface between provider and
ConfigurationPolicyPrefStore into a observer-based mechanism, so we wouldn't
need the WeakPtr hack here. Is that planned for a different CL?

[danno, 2010/12/03 17:05:38]

There's plenty left to do, this work is only the first step. Refactoring the
windows provider to work like the others is the next, and then changing the
notification interface. I'll add a TODO.
On 2010/12/02 18:16:00, Mattias Nissler wrote:

+      AsynchronousPolicyProvider::Delegate* delegate,
+      int reload_interval_minutes);
+
+  // Triggers initial policy load and schedules fallback reload.
+  void Init();
+
+  // Gets the current dictionary value object. Ownership of the returned value
+  // is transferred to the caller.
+  DictionaryValue* GetPolicy();
+
+  // Reloads policy, sending notification of changes if necessary. Must be
+  // called on the file thread.
+  void Reload();
+
+  // Stops any pending reload tasks.
+  void Stop();
+
+ private:
+  friend class AsynchronousPolicyLoaderTest;
+  // FileBasedPolicyLoader objects should only be deleted by

[Mattias Nissler (ping if slow), 2010/12/02 18:16:00]

newline before comment?

[danno, 2010/12/03 17:05:38]

Done.

+  // RefCountedThreadSafe.
+  friend class base::RefCountedThreadSafe<AsynchronousPolicyLoader>;
+  virtual ~AsynchronousPolicyLoader() {}
+
+  // Schedules a reload task to run when |delay| expires. Must be called on the
+  // file thread.
+  void ScheduleReloadTask(const base::TimeDelta& delay);
+
+  // Schedules a reload task to run after the number of minutes specified
+  // in |reload_interval_minutes_|. Must be called on the file thread.
+  void ScheduleFallbackReloadTask();
+
+  // Invoked from the reload task on the file thread.
+  void ReloadFromTask();
+
+  // Notifies the policy provider to send out a policy changed notification.
+  // Must be called on |origin_loop_|.
+  void NotifyPolicyChanged();
+
+  // The provider this loader is associated with. Access only on the thread that
+  // called the constructor. See |origin_loop_| below.
+  base::WeakPtr<ConfigurationPolicyProvider> provider_;
+
+  scoped_ptr<AsynchronousPolicyProvider::Delegate> delegate_;
+
+  // Protects |policy_|.

[Mattias Nissler (ping if slow), 2010/12/02 18:16:00]

Is that still necessary? I thought we decided to access |policy_| only from the
UI thread, and the lock should go away in that case.

[danno, 2010/12/03 17:05:38]

Done.

+  Lock lock_;
+
+  // The current policy definition.
+  scoped_ptr<DictionaryValue> policy_;
+
+  // The message loop on which this object was constructed and |provider_|
+  // received on. Recorded so we can call back into the non thread safe provider
+  // to fire the notification.
+  MessageLoop* origin_loop_;
+
+  // The reload task. Access only on the file thread. Holds a reference to the
+  // currently posted task, so we can cancel and repost it if necessary.
+  CancelableTask* reload_task_;
+
+  // The interval in minutes that a policy reload will be triggered as a
+  // fallback even if the delegate doesn't indicate that one is needed.
+  const int reload_interval_minutes_;
+
+  DISALLOW_COPY_AND_ASSIGN(AsynchronousPolicyLoader);
+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_POLICY_ASYNCHRONOUS_POLICY_LOADER_H_