Reland of Moving previews code from components/ to chrome/

components/previews/core/previews_io_data.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_IO_DATA_H_
 #define COMPONENTS_PREVIEWS_CORE_PREVIEWS_IO_DATA_H_
 
 #include <memory>
 #include <string>
 
+#include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/time/time.h"
 #include "components/previews/core/previews_decider.h"
 #include "components/previews/core/previews_experiments.h"
 
 class GURL;
 
 namespace net {
 class URLRequest;
 }
 
 namespace previews {
 class PreviewsBlackList;
 class PreviewsOptOutStore;
 class PreviewsUIService;
 
+typedef base::Callback<bool(PreviewsType)> PreviewsIsEnabledCallback;
+
 // A class to manage the IO portion of inter-thread communication between
 // previews/ objects. Created on the UI thread, but used only on the IO thread
 // after initialization.
 class PreviewsIOData : public PreviewsDecider {
  public:
   PreviewsIOData(
       const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner,
       const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);
   ~PreviewsIOData() override;
 
   // 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);
+                  std::unique_ptr<PreviewsOptOutStore> previews_opt_out_store,
+                  const PreviewsIsEnabledCallback& is_enabled_callback);
 
   // Adds a navigation to |url| to the black list with result |opt_out|.
   void AddPreviewNavigation(const GURL& url, bool opt_out, PreviewsType type);
 
   // Clears the history of the black list between |begin_time| and |end_time|,
   // both inclusive.
   void ClearBlackList(base::Time begin_time, base::Time end_time);
 
   // The previews black list that decides whether a navigation can use previews.
   PreviewsBlackList* black_list() const { return previews_black_list_.get(); }
@@ skipping 14 matching lines @@
 
   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
   // happening on the IO thread.
   scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
+  // Whether the preview is enabled. Valid after Initialize() is called.
+  PreviewsIsEnabledCallback is_enabled_callback_;
+
   base::WeakPtrFactory<PreviewsIOData> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PreviewsIOData);
 };
 
 }  // namespace previews
 
 #endif  // COMPONENTS_PREVIEWS_CORE_PREVIEWS_IO_DATA_H_