sync: Handle POLL jobs in separate a code path

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 7190bdf62113c991fd2ea1632d67c135479d4e71..61351b782e5ebb9ab6329569fb9869dbbb707c2e 100644
--- a/sync/engine/sync_scheduler_impl.h
+++ b/sync/engine/sync_scheduler_impl.h
@@ -169,25 +169,25 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl : public SyncScheduler {
                        const base::Closure& task,
                        base::TimeDelta delay);
 
-  // Helper to assemble a job and post a delayed task to sync.
-  void ScheduleSyncSessionJob(const tracked_objects::Location& loc,
-                              scoped_ptr<SyncSessionJob> job);
-
-  // Invoke the Syncer to perform a sync.
+  // Invoke the Syncer to perform a non-poll job.
   bool DoSyncSessionJob(scoped_ptr<SyncSessionJob> job,
                         JobPriority priority);
 
+  // Returns whether or not it's safe to run a poll job at this time.
+  bool ShouldPoll();
+
+  // Invoke the Syncer to perform a poll job.
+  void DoPollSyncSessionJob(scoped_ptr<SyncSessionJob> job);
+
   // Called after the Syncer has performed the sync represented by |job|, to
   // reset our state.  |exited_prematurely| is true if the Syncer did not
   // cycle from job.start_step() to job.end_step(), likely because the
   // scheduler was forced to quit the job mid-way through.
-  bool FinishSyncSessionJob(scoped_ptr<SyncSessionJob> job,
+  bool FinishSyncSessionJob(SyncSessionJob* job,
                             bool exited_prematurely);
 
-  // Helper to FinishSyncSessionJob to schedule the next sync operation.
-  // |succeeded| carries the return value of |old_job|->Finish.
-  void ScheduleNextSync(scoped_ptr<SyncSessionJob> finished_job,
-                        bool succeeded);
+  // Helper to schedule retries of a failed configure or nudge job.
+  void ScheduleNextSync(scoped_ptr<SyncSessionJob> finished_job);
 
   // Helper to configure polling intervals. Used by Start and ScheduleNextSync.
   void AdjustPolling(const SyncSessionJob* old_job);
@@ -214,6 +214,11 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl : public SyncScheduler {
   // 'Impl' here refers to real implementation of public functions, running on
   // |thread_|.
   void StopImpl(const base::Closure& callback);
+
+  // 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,
+  // then post a delayed task to run it.  It may also choose to drop the job or
+  // save it for later, depending on the scheduler's current state.
   void ScheduleNudgeImpl(
       const base::TimeDelta& delay,
       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source,