Generalize Previews Type code

components/previews/core/previews_ui_service.h

 // Copyright 2016 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_PREVIEWS_CORE_PREVIEWS_UI_SERVICE_H_
 #define COMPONENTS_PREVIEWS_CORE_PREVIEWS_UI_SERVICE_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
+#include "components/previews/core/previews_experiments.h"
 #include "components/previews/core/previews_opt_out_store.h"
 
 class GURL;
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace previews {
 class PreviewsIOData;
@@ skipping 28 matching lines @@
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   base::WeakPtrFactory<PreviewsUIService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PreviewsUIService);
 };
 
 }  // namespace previews
 
 #endif  // COMPONENTS_PREVIEWS_CORE_PREVIEWS_UI_SERVICE_H_