[Sync] Sync types never recovers from throttle

components/sync/engine_impl/sync_scheduler_impl.h

 // Copyright 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 COMPONENTS_SYNC_ENGINE_IMPL_SYNC_SCHEDULER_IMPL_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_SYNC_SCHEDULER_IMPL_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 130 matching lines @@
   void DoPollSyncCycleJob();
 
   // Helper function to calculate poll interval.
   base::TimeDelta GetPollInterval();
 
   // Adjusts the poll timer to account for new poll interval, and possibly
   // resets the poll interval, depedning on the flag's value.
   void AdjustPolling(PollAdjustType type);
 
   // Helper to restart pending_wakeup_timer_.
+  // This function need to be called in 3 conditions, backoff/throttling
+  // happens, unbackoff/unthrottling happens and after |PerformDelayedNudge|
+  // runs.
+  // This function is for scheduling unbackoff/unthrottling jobs, and the
+  // poriority is, global unbackoff/unthrottling job first, if there is no
+  //  global backoff/throttling, then try to schedule types
+  // unbackoff/unthrottling job.
   void RestartWaiting();
 
   // Determines if we're allowed to contact the server right now.
   bool CanRunJobNow(JobPriority priority);
 
   // Determines if we're allowed to contact the server right now.
   bool CanRunNudgeJobNow(JobPriority priority);
 
   // If the scheduler's current state supports it, this will create a job based
   // on the passed in parameters and coalesce it with any other pending jobs,
@@ skipping 48 matching lines @@
   // containing data like initial_sync_ended.  Important when the client starts
   // up and does not need to perform an initial sync.
   void SendInitialSnapshot();
 
   // This is used for histogramming and analysis of ScheduleNudge* APIs.
   // SyncScheduler is the ultimate choke-point for all such invocations (with
   // and without InvalidationState variants, all NudgeSources, etc) and as such
   // is the most flexible place to do this bookkeeping.
   void UpdateNudgeTimeRecords(ModelTypeSet types);
 
+  bool IsEarlierThanCurrentPendingJob(const base::TimeDelta& delay);
+
   // Used for logging.
   const std::string name_;
 
   // Set in Start(), unset in Stop().
   bool started_;
 
   // Modifiable versions of kDefaultLongPollIntervalSeconds which can be
   // updated by the server.
   base::TimeDelta syncer_short_poll_interval_seconds_;
   base::TimeDelta syncer_long_poll_interval_seconds_;
 
   // Timer for polling. Restarted on each successful poll, and when entering
   // normal sync mode or exiting an error state. Not active in configuration
   // mode.
   base::OneShotTimer poll_timer_;
 
   // The mode of operation.
   Mode mode_;
 
   // Current wait state.  Null if we're not in backoff and not throttled.
   std::unique_ptr<WaitInterval> wait_interval_;
 
   std::unique_ptr<BackoffDelayProvider> delay_provider_;
 
+  // TODO(gangwu): http://crbug.com/714868 too many timers in this class, try to
+  // reduce them.
   // The event that will wake us up.
   // When the whole client got throttling or backoff, we will delay this timer
   // as well.
   base::OneShotTimer pending_wakeup_timer_;
 
   // Storage for variables related to an in-progress configure request.  Note
   // that (mode_ != CONFIGURATION_MODE) \implies !pending_configure_params_.
   std::unique_ptr<ConfigurationParams> pending_configure_params_;
 
   std::unique_ptr<ClearParams> pending_clear_params_;
@@ skipping 31 matching lines @@
   bool ignore_auth_credentials_;
 
   base::WeakPtrFactory<SyncSchedulerImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncSchedulerImpl);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_SYNC_SCHEDULER_IMPL_H_