Move AsyncPolicyProvider, etc. to components/policy/.

chrome/browser/policy/async_policy_loader.h

-// Copyright (c) 2012 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_ASYNC_POLICY_LOADER_H_
-#define CHROME_BROWSER_POLICY_ASYNC_POLICY_LOADER_H_
-
-#include "base/callback.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/time/time.h"
-#include "components/policy/core/common/schema_map.h"
-
-namespace base {
-class SequencedTaskRunner;
-}
-
-namespace policy {
-
-class PolicyBundle;
-
-// Base implementation for platform-specific policy loaders. Together with the
-// AsyncPolicyProvider, this base implementation takes care of the initial load,
-// periodic reloads, watching file changes, refreshing policies and object
-// lifetime.
-//
-// All methods are invoked on the background |task_runner_|, including the
-// destructor. The only exceptions are the constructor (which may be called on
-// any thread), and the initial Load() which is called on the thread that owns
-// the provider.
-// LastModificationTime() is also invoked once on that thread at startup.
-class AsyncPolicyLoader {
- public:
-  explicit AsyncPolicyLoader(
-      scoped_refptr<base::SequencedTaskRunner> task_runner);
-  virtual ~AsyncPolicyLoader();
-
-  // Gets a SequencedTaskRunner backed by the background thread.
-  base::SequencedTaskRunner* task_runner() const { return task_runner_.get(); }
-
-  // Returns the currently configured policies. Load() is always invoked on
-  // the background thread, except for the initial Load() at startup which is
-  // invoked from the thread that owns the provider.
-  virtual scoped_ptr<PolicyBundle> Load() = 0;
-
-  // Allows implementations to finalize their initialization on the background
-  // thread (e.g. setup file watchers).
-  virtual void InitOnBackgroundThread() = 0;
-
-  // Implementations should return the time of the last modification detected,
-  // or base::Time() if it doesn't apply, which is the default.
-  virtual base::Time LastModificationTime();
-
-  // Used by the AsyncPolicyProvider to do the initial Load(). The first load
-  // is also used to initialize |last_modification_time_| and
-  // |schema_map_|.
-  scoped_ptr<PolicyBundle> InitialLoad(const scoped_refptr<SchemaMap>& schemas);
-
-  // Implementations should invoke Reload() when a change is detected. This
-  // must be invoked from the background thread and will trigger a Load(),
-  // and pass the returned bundle to the provider.
-  // The load is immediate when |force| is true. Otherwise, the loader
-  // reschedules the reload until the LastModificationTime() is a couple of
-  // seconds in the past. This mitigates the problem of reading files that are
-  // currently being written to, and whose contents are incomplete.
-  // A reload is posted periodically, if it hasn't been triggered recently. This
-  // makes sure the policies are reloaded if the update events aren't triggered.
-  void Reload(bool force);
-
-  const scoped_refptr<SchemaMap>& schema_map() const { return schema_map_; }
-
- private:
-  // Allow AsyncPolicyProvider to call Init().
-  friend class AsyncPolicyProvider;
-
-  typedef base::Callback<void(scoped_ptr<PolicyBundle>)> UpdateCallback;
-
-  // Used by the AsyncPolicyProvider to install the |update_callback_|.
-  // Invoked on the background thread.
-  void Init(const UpdateCallback& update_callback);
-
-  // Used by the AsyncPolicyProvider to reload with an updated SchemaMap.
-  void RefreshPolicies(scoped_refptr<SchemaMap> schema_map);
-
-  // Cancels any pending periodic reload and posts one |delay| time units from
-  // now.
-  void ScheduleNextReload(base::TimeDelta delay);
-
-  // Checks if the underlying files haven't changed recently, by checking the
-  // LastModificationTime(). |delay| is updated with a suggested time to wait
-  // before retrying when this returns false.
-  bool IsSafeToReload(const base::Time& now, base::TimeDelta* delay);
-
-  // Task runner to run background threads.
-  scoped_refptr<base::SequencedTaskRunner> task_runner_;
-
-  // Callback for updates, passed in Init().
-  UpdateCallback update_callback_;
-
-  // Used to get WeakPtrs for the periodic reload task.
-  base::WeakPtrFactory<AsyncPolicyLoader> weak_factory_;
-
-  // Records last known modification timestamp.
-  base::Time last_modification_time_;
-
-  // The wall clock time at which the last modification timestamp was
-  // recorded.  It's better to not assume the file notification time and the
-  // wall clock times come from the same source, just in case there is some
-  // non-local filesystem involved.
-  base::Time last_modification_clock_;
-
-  // The current policy schemas that this provider should load.
-  scoped_refptr<SchemaMap> schema_map_;
-
-  DISALLOW_COPY_AND_ASSIGN(AsyncPolicyLoader);
-};
-
-}  // namespace policy
-
-#endif  // CHROME_BROWSER_POLICY_ASYNC_POLICY_LOADER_H_