[Offline pages] Adding ArchiveManager to abstract offline archives management

components/offline_pages/archive_manager.h

Index: components/offline_pages/archive_manager.h
diff --git a/components/offline_pages/archive_manager.h b/components/offline_pages/archive_manager.h
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index 0000000000000000000000000000000000000000..f60370ce0d3debced98052817df3e80adbc9d160
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+++ b/components/offline_pages/archive_manager.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_OFFLINE_PAGES_ARCHIVE_MANAGER_H_
+#define COMPONENTS_OFFLINE_PAGES_ARCHIVE_MANAGER_H_
+
+#include <vector>
+
+#include "base/callback_forward.h"
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+
+namespace base {
+class SequencedTaskRunner;
+}  // namespace base
+
+namespace offline_pages {
+
+// Class that manages all archive files for offline pages. They are all stored
+// in a specific archive directory.
+// All tasks are performed using |task_runner_|.
+class ArchiveManager {
+ public:
+  ArchiveManager(const base::FilePath& archives_dir,
+                 const scoped_refptr<base::SequencedTaskRunner>& task_runner);
+  virtual ~ArchiveManager();
+
+  // Creates archives directory of one does not exist yet;

[Dmitry Titov, 2016/05/16 21:04:56]

of->if

[fgorski, 2016/05/16 21:23:01]

Done.

+  virtual void EnsureArchivesDirCreated(const base::Closure& callback);
+
+  // Checks whether an archive with specified |archive_path| exists.
+  // It is considered successful to attempt to delete a file that does not

[Dmitry Titov, 2016/05/16 21:04:56]

copy/pasted comment?

[fgorski, 2016/05/16 21:23:01]

Done.

+  // exist.
+  virtual void ExistsArchive(const base::FilePath& archive_path,
+                             const base::Callback<void(bool)>& callback);
+
+  // Deletes an archive with specified |archive_path|.
+  // It is considered successful to attempt to delete a file that does not
+  // exist.
+  virtual void DeleteArchive(const base::FilePath& archive_path,
+                             const base::Callback<void(bool)>& callback);
+
+  // Deletes multiple archives that are specified in |archive_paths|.
+  virtual void DeleteArchives(const std::vector<base::FilePath>& archive_paths,

[Dmitry Titov, 2016/05/16 21:04:56]

I'd suggest DeleteMultipleArchives to make these names more visibly distinct.

[fgorski, 2016/05/16 21:23:01]

Done.

+                              const base::Callback<void(bool)>& callback);
+
+ private:
+  // Path under which all of the managed archives should be stored.
+  base::FilePath archives_dir_;
+  // Task runner for running file operations.
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_ARCHIVE_MANAGER_H_