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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_
      6 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_
      7 
      8 #include "base/bind.h"
      9 #include "base/gtest_prod_util.h"
     10 #include "base/time/time.h"
     11 #include "base/timer/timer.h"
     12 
     13 class PrefService;
     14 
     15 namespace chrome_variations {
     16 
     17 // A helper class that makes VariationsService requests at the correct times.
     18 class VariationsRequestScheduler {
     19  public:
     20   virtual ~VariationsRequestScheduler();
     21 
     22   // Starts the task. This can be a repeated event or a one-off.
     23   virtual void Start();
     24 
     25   // Resets the scheduler if it is currently on a timer.
     26   virtual void Reset();
     27 
     28   // Schedules a fetch shortly, for example to re-try the initial request which
     29   // may have failed.
     30   void ScheduleFetchShortly();
     31 
     32   // Called when the application has been foregrounded. This may fetch a new
     33   // seed.
     34   virtual void OnAppEnterForeground();
     35 
     36   // Factory method for this class.
     37   static VariationsRequestScheduler* Create(const base::Closure& task,
     38                                             PrefService* local_state);
     39 
     40  protected:
     41   // |task| is the closure to call when the scheduler deems ready.
     42   explicit VariationsRequestScheduler(const base::Closure& task);
     43 
     44   // Getter for derived classes.
     45   base::Closure task() const;
     46 
     47  private:
     48   FRIEND_TEST_ALL_PREFIXES(VariationsRequestSchedulerTest,
     49                            ScheduleFetchShortly);
     50 
     51   // The task scheduled by this class.
     52   base::Closure task_;
     53 
     54   // The timer used to repeatedly ping the server. Keep this as an instance
     55   // member so if VariationsRequestScheduler goes out of scope, the timer is
     56   // automatically canceled.
     57   base::RepeatingTimer<VariationsRequestScheduler> timer_;
     58 
     59   // A one-shot timer used for scheduling out-of-band fetches.
     60   base::OneShotTimer<VariationsRequestScheduler> one_shot_timer_;
     61 
     62   DISALLOW_COPY_AND_ASSIGN(VariationsRequestScheduler);
     63 };
     64 
     65 }  // namespace chrome_variations
     66 
     67 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_
     68