Client-side changes to support retry GU.

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 81a4fcf68d1534d0c2bd703102294d0e71ab7a52..68d2a802ed9680b5aea9ed07313e87dca0b431d1 100644
--- a/sync/engine/sync_scheduler_impl.h
+++ b/sync/engine/sync_scheduler_impl.h
@@ -89,6 +89,10 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   virtual void OnReceivedClientInvalidationHintBufferSize(int size) OVERRIDE;
   virtual void OnSyncProtocolError(
       const sessions::SyncSessionSnapshot& snapshot) OVERRIDE;
+  virtual void OnReceivedGuRetryDelay(const base::TimeDelta& delay) OVERRIDE;
+
+  // Returns true if the client is currently in exponential backoff.
+  bool IsBackingOff() const;
 
  private:
   enum JobPriority {
@@ -167,6 +171,9 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // Invoke the Syncer to perform a poll job.
   void DoPollSyncSessionJob();
 
+  // Invoke the Syncer to perform a retry job.
+  void DoRetrySyncSessionJob();
+
   // Helper function to calculate poll interval.
   base::TimeDelta GetPollInterval();
 
@@ -191,9 +198,6 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
       const base::TimeDelta& delay,
       const tracked_objects::Location& nudge_location);
 
-  // Returns true if the client is currently in exponential backoff.
-  bool IsBackingOff() const;
-
   // Helper to signal all listeners registered with |session_context_|.
   void Notify(SyncEngineEvent::EventCause cause);
 
@@ -230,6 +234,9 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // Creates a session for a poll and performs the sync.
   void PollTimerCallback();
 
+  // Creates a session for a retry and performs the sync.
+  void RetryTimerCallback();
+
   // Returns the set of types that are enabled and not currently throttled.
   ModelTypeSet GetEnabledAndUnthrottledTypes();
 
@@ -336,6 +343,9 @@ class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
   // to be const and alleviate threading concerns.
   base::WeakPtrFactory<SyncSchedulerImpl> weak_ptr_factory_for_weak_handle_;
 
+  // One-shot timer for scheduling GU retry according to delay set by server.
+  base::OneShotTimer<SyncSchedulerImpl> retry_timer_;
+
   DISALLOW_COPY_AND_ASSIGN(SyncSchedulerImpl);
 };