[Sync] Add support for server controlled nudge delays

sync/engine/sync_scheduler_impl.h

Index: sync/engine/sync_scheduler_impl.h
diff --git a/sync/engine/sync_scheduler_impl.h b/sync/engine/sync_scheduler_impl.h
index 7cb295b37c8f578851edd83e8c95c5fdf66a49c2..756690b35aae0bcb3ca45238bf9cd809490a8a0c 100644
--- a/sync/engine/sync_scheduler_impl.h
+++ b/sync/engine/sync_scheduler_impl.h
@@ -56,23 +56,18 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
       const ConfigurationParams& params) OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void ScheduleLocalNudge(
-      const base::TimeDelta& desired_delay,
       ModelTypeSet types,
       const tracked_objects::Location& nudge_location) OVERRIDE;
   virtual void ScheduleLocalRefreshRequest(
-      const base::TimeDelta& desired_delay,
       ModelTypeSet types,
       const tracked_objects::Location& nudge_location) OVERRIDE;
   virtual void ScheduleInvalidationNudge(
-      const base::TimeDelta& desired_delay,
       syncer::ModelType type,
       scoped_ptr<InvalidationInterface> invalidation,
       const tracked_objects::Location& nudge_location) OVERRIDE;
   virtual void ScheduleInitialSyncNudge(syncer::ModelType model_type) OVERRIDE;
   virtual void SetNotificationsEnabled(bool notifications_enabled) OVERRIDE;
 
-  virtual base::TimeDelta GetSessionsCommitDelay() const OVERRIDE;
-
   virtual void OnCredentialsUpdated() OVERRIDE;
   virtual void OnConnectionStatusChange() OVERRIDE;
 
@@ -86,8 +81,8 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
       const base::TimeDelta& new_interval) OVERRIDE;
   virtual void OnReceivedLongPollIntervalUpdate(
       const base::TimeDelta& new_interval) OVERRIDE;
-  virtual void OnReceivedSessionsCommitDelay(
-      const base::TimeDelta& new_delay) OVERRIDE;
+  virtual void OnReceivedCustomNudgeDelays(
+      const std::map<ModelType, int>& nudge_delays) OVERRIDE;
   virtual void OnReceivedClientInvalidationHintBufferSize(int size) OVERRIDE;
   virtual void OnSyncProtocolError(
       const SyncProtocolError& sync_protocol_error) OVERRIDE;
@@ -97,6 +92,9 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // Returns true if the client is currently in exponential backoff.
   bool IsBackingOff() const;
 
+  // Returns the nudge delay to be used based on |types|.
+  base::TimeDelta GetNudgeDelayForTypes(ModelTypeSet types) const;
+
  private:
   enum JobPriority {
     // Non-canary jobs respect exponential backoff.
@@ -150,6 +148,8 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
 
   static const char* GetModeString(Mode mode);
 
+  void SetDefaultNudgeDelay(int delay_ms);
+
   // Invoke the syncer to perform a nudge job.
   void DoNudgeSyncSessionJob(JobPriority priority);
 
@@ -251,8 +251,9 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   base::TimeDelta syncer_short_poll_interval_seconds_;
   base::TimeDelta syncer_long_poll_interval_seconds_;
 
-  // Server-tweakable sessions commit delay.
-  base::TimeDelta sessions_commit_delay_;
+  // Server-tweakable custom nudge delays.

[rlarocque, 2014/08/20 00:13:31]

The nudge delay tracking code is somewhat complicated, and reasonably
self-contained.  Maybe you could pull these member variables, and all the
functions that reference them, into a separate class?

SyncSchedulerImpl is already too big.  Let's not make it worse.

[Nicolas Zea, 2014/08/20 22:49:43]

Discussed offline, moved this state into NudgeTracker/DataTypeTracker.

+  int minimum_nudge_delay_ms_;
+  std::map<ModelType, base::TimeDelta> nudge_delays_;
 
   // Periodic timer for polling.  See AdjustPolling.
   base::RepeatingTimer<SyncSchedulerImpl> poll_timer_;