[Sync] Refactoring of sync integration test checkers to remove boilerplate await methods.

components/sync/driver/non_blocking_data_type_controller.h

 // Copyright 2014 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_NON_BLOCKING_DATA_TYPE_CONTROLLER_H_
 #define COMPONENTS_SYNC_DRIVER_NON_BLOCKING_DATA_TYPE_CONTROLLER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 18 matching lines @@
 // - RunOnModelThread
 // - RunOnUIThread
 class NonBlockingDataTypeController : public sync_driver::DataTypeController {
  public:
   // |dump_stack| is called when an unrecoverable error occurs.
   NonBlockingDataTypeController(syncer::ModelType type,
                                 const base::Closure& dump_stack,
                                 sync_driver::SyncClient* sync_client);
   ~NonBlockingDataTypeController() override;
 
-  // DataTypeController interface.
+  // DataTypeController implementation.
   bool ShouldLoadModelBeforeConfigure() const override;
   void LoadModels(const ModelLoadCallback& model_load_callback) override;
   void GetAllNodes(const AllNodesCallback& callback) override;
 
   // Registers non-blocking data type with sync backend. In the process the
   // activation context is passed to ModelTypeRegistry, where ModelTypeWorker
   // gets created and connected with ModelTypeProcessor.
   void RegisterWithBackend(
       sync_driver::BackendDataTypeConfigurer* configurer) override;
   void StartAssociating(const StartCallback& start_callback) override;
@@ skipping 52 matching lines @@
   // something the first time after the type is enabled.
   // TODO(crbug.com/647505): Remove this once the DTM handles things better.
   bool activated_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(NonBlockingDataTypeController);
 };
 
 }  // namespace sync_driver_v2
 
 #endif  // COMPONENTS_SYNC_DRIVER_NON_BLOCKING_DATA_TYPE_CONTROLLER_H_