[Sync] Consolidate DataTypeController methods that post on the backend thread

chrome/browser/sync/glue/extension_setting_data_type_controller.h

Index: chrome/browser/sync/glue/extension_setting_data_type_controller.h
diff --git a/chrome/browser/sync/glue/extension_setting_data_type_controller.h b/chrome/browser/sync/glue/extension_setting_data_type_controller.h
index cd72b6aeadffa620792c23695bacef266c18de19..5fc7d7962b0aee4af0c526ce400dbf50bc819fba 100644
--- a/chrome/browser/sync/glue/extension_setting_data_type_controller.h
+++ b/chrome/browser/sync/glue/extension_setting_data_type_controller.h
@@ -39,20 +39,20 @@ class ExtensionSettingDataTypeController
 
  private:
   // NonFrontendDataTypeController implementation.
+  virtual bool PostTaskOnBackendThread(
+      const tracked_objects::Location& from_here,
+      const base::Closure& task) OVERRIDE;
   virtual bool StartModels() OVERRIDE;
-  virtual bool StartAssociationAsync() OVERRIDE;
   virtual void CreateSyncComponents() OVERRIDE;
-  virtual bool StopAssociationAsync() OVERRIDE;
   virtual void RecordUnrecoverableError(
       const tracked_objects::Location& from_here,
       const std::string& message) OVERRIDE;
   virtual void RecordAssociationTime(base::TimeDelta time) OVERRIDE;
   virtual void RecordStartFailure(StartResult result) OVERRIDE;
 
-  // Starts sync association with |settings_service|.  Callback from
-  // RunWithSettings of |extension_settings_ui_wrapper_| on FILE thread.
-  void StartAssociationWithExtensionSettingsService(
-      SyncableService* settings_service);
+  // Used by PostTaskOnBackendThread().
+  void RunTaskOnBackendThread(const base::Closure& task,
+                              SyncableService* settings_service);
 
   // Either EXTENSION_SETTINGS or APP_SETTINGS.
   syncable::ModelType type_;