Channel all low lever scheduling calls through single function

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 60d1c3873af77d4273790ade9ff52494836eda0b..4ffbf6f71e5abd04f12b42755601dd200d7cbaf3 100644
--- a/sync/engine/sync_scheduler_impl.h
+++ b/sync/engine/sync_scheduler_impl.h
@@ -167,6 +167,9 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // Invoke the Syncer to perform a poll job.
   void DoPollSyncSessionJob();
 
+  // 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);
@@ -204,6 +207,8 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // priority.
   void TryCanaryJob();
 
+  void TrySyncSessionJob(JobPriority priority);
+
   // Transitions out of the THROTTLED WaitInterval then calls TryCanaryJob().
   void Unthrottle();
 
@@ -309,6 +314,11 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // after credentials are updated.
   bool do_poll_after_credentials_updated_;
 
+  // TryJob might get called for multiple reasons. It should only call
+  // DoPollSyncSessionJob after some time since the last attempt.
+  // last_poll_reset_ keeps track of when was last attempt.
+  base::TimeTicks last_poll_reset_;
+
   base::WeakPtrFactory<SyncSchedulerImpl> weak_ptr_factory_;
 
   // A second factory specially for weak_handle_this_, to allow the handle