[sync] Set up notification-free infra for triggering local sync refresh

components/sync_driver/sync_service.h

 // Copyright 2015 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_DRIVER_SYNC_SERVICE_H_
 #define COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 85 matching lines @@
   virtual bool IsSyncAllowed() const = 0;
 
   // Returns true if sync is fully initialized and active. This implies that
   // an initial configuration has successfully completed, although there may
   // be datatype specific, auth, or other transient errors. To see which
   // datetypes are actually syncing, see GetActiveTypes() below.
   // Note that if sync is in backup or rollback mode, IsSyncActive() will be
   // false.
   virtual bool IsSyncActive() const = 0;
 
+  // Triggers a GetUpdates call for the specified |types|, pulling any new data
+  // from the sync server.
+  virtual void TriggerRefresh(const syncer::ModelTypeSet& types) = 0;
+
   // Get the set of current active data types (those chosen or configured by
   // the user which have not also encountered a runtime error).
   // Note that if the Sync engine is in the middle of a configuration, this
   // will the the empty set. Once the configuration completes the set will
   // be updated.
   virtual syncer::ModelTypeSet GetActiveDataTypes() const = 0;
 
   // Returns the SyncClient instance associated with this service.
   virtual SyncClient* GetSyncClient() const = 0;
 
@@ skipping 207 matching lines @@
  protected:
   SyncService() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncService);
 };
 
 }  // namespace sync_driver
 
 #endif  // COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_H_