Adding an IO Data and keyed service to previews/

components/previews/previews_ui_service.h

Index: components/previews/previews_ui_service.h
diff --git a/components/previews/previews_ui_service.h b/components/previews/previews_ui_service.h
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index 0000000000000000000000000000000000000000..195b0979b82d1d4dd47621ad58888584d25fb0c3
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+++ b/components/previews/previews_ui_service.h
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+// 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_PREVIEWS_UI_SERVICE_H_
+#define COMPONENTS_PREVIEWS_PREVIEWS_UI_SERVICE_H_
+
+#include <string>
+
+#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/threading/thread_checker.h"
+
+namespace previews {
+class PreviewsIOData;
+
+// A class to manage the UI portion of inter-thread communication between
+// previews/ objects. Created and used on the UI thread.
+class PreviewsUIService {
+ public:
+  PreviewsUIService(
+      PreviewsIOData* previews_io_data,
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);
+  virtual ~PreviewsUIService();
+
+  // Sets |io_data_| to |io_data| to allow calls from the UI thread to the IO
+  // thread. Virtualized in testing.
+  virtual void SetIOData(base::WeakPtr<PreviewsIOData> io_data);
+
+ private:
+  // The IO thread portion of the inter-thread communication for previews/.
+  base::WeakPtr<previews::PreviewsIOData> io_data_;
+
+  base::ThreadChecker thread_checker_;
+
+  // The IO thread task runner. Used to post tasks to |io_data_|.
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+
+  base::WeakPtrFactory<PreviewsUIService> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreviewsUIService);
+};
+
+}  // namespace previews
+
+#endif  // COMPONENTS_PREVIEWS_PREVIEWS_UI_SERVICE_H_