Adding a SQL implementation of the backing store for previews opt outs

components/previews/core/previews_io_data.h

Index: components/previews/core/previews_io_data.h
diff --git a/components/previews/core/previews_io_data.h b/components/previews/core/previews_io_data.h
index ce157858d5a44171cb5c1728a2db8ae5c98f5529..0176d2446baa8b86dd634398a6871f78e9b67973 100644
--- a/components/previews/core/previews_io_data.h
+++ b/components/previews/core/previews_io_data.h
@@ -31,22 +31,21 @@ class PreviewsIOData {
   // Stores |previews_ui_service| as |previews_ui_service_| and posts a task to
   // InitializeOnIOThread on the IO thread.
   void Initialize(base::WeakPtr<PreviewsUIService> previews_ui_service,
                   std::unique_ptr<PreviewsOptOutStore> previews_opt_out_store);
 
   PreviewsBlackList* black_list() const { return previews_black_list_.get(); }
 
  protected:
   // Posts a task to SetIOData for |previews_ui_service_| on the UI thread with
   // a weak pointer to |this|. Virtualized for testing.
-  virtual void InitializeOnIOThread(
-      std::unique_ptr<PreviewsOptOutStore> previews_opt_out_store);
+  virtual void InitializeOnIOThread();
 
  private:
   // The UI thread portion of the inter-thread communication for previews.
   base::WeakPtr<PreviewsUIService> previews_ui_service_;
 
   std::unique_ptr<PreviewsBlackList> previews_black_list_;
 
   // The UI and IO thread task runners. |ui_task_runner_| is used to post
   // tasks to |previews_ui_service_|, and |io_task_runner_| is used to post from
   // Initialize to InitializeOnIOThread as well as verify that execution is