[Sync] Minor refactor around SyncCycle and ModelTypeSet usage.

components/sync/engine_impl/cycle/sync_cycle.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_CYCLE_SYNC_CYCLE_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_CYCLE_SYNC_CYCLE_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 70 matching lines @@
     // Called when server wants to schedule a retry GU.
     virtual void OnReceivedGuRetryDelay(const base::TimeDelta& delay) = 0;
 
     // Called when server requests a migration.
     virtual void OnReceivedMigrationRequest(ModelTypeSet types) = 0;
 
    protected:
     virtual ~Delegate() {}
   };
 
-  // Build a cycle without a nudge tracker.  Used for poll or configure type
-  // sync cycles.
-  static SyncCycle* Build(SyncCycleContext* context, Delegate* delegate);
+  SyncCycle(SyncCycleContext* context, Delegate* delegate);
   ~SyncCycle();
 
   // Builds a thread-safe and read-only copy of the current cycle state.
   SyncCycleSnapshot TakeSnapshot() const;
   SyncCycleSnapshot TakeSnapshotWithSource(
       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource legacy_updates_source)
       const;
 
   // Builds and sends a snapshot to the cycle context's listeners.
   void SendSyncCycleEndEventNotification(
       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source);
   void SendEventNotification(SyncCycleEvent::EventCause cause);
 
   void SendProtocolEvent(const ProtocolEvent& event);
 
   // TODO(akalin): Split this into context() and mutable_context().
   SyncCycleContext* context() const { return context_; }
   Delegate* delegate() const { return delegate_; }
   const StatusController& status_controller() const {
     return *status_controller_.get();
   }
   StatusController* mutable_status_controller() {
     return status_controller_.get();
   }
 
  private:
-  SyncCycle(SyncCycleContext* context, Delegate* delegate);
-
   // The context for this cycle, guaranteed to outlive |this|.
   SyncCycleContext* const context_;
 
   // The delegate for this cycle, must never be null.
   Delegate* const delegate_;
 
   // Our controller for various status and error counters.
   std::unique_ptr<StatusController> status_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncCycle);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_CYCLE_SYNC_CYCLE_H_