[Offline] Adding archiver interface

components/offline_pages/offline_page_archiver.h

+// Copyright 2015 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_OFFLINE_PAGE_ARCHIVER_H_
+#define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ARCHIVER_H_
+
+#include "base/files/file_path.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+// Interface of a class responsible for creation of the archive for offline use.
+class OfflinePageArchiver {
+ public:
+  // Represents an in progress request to archive a page.
+  struct Request {
+   public:
+    explicit Request(const GURL& url);
+    ~Request();
+    GURL url;
+  };
+
+  //  Interface of the clients that requests to archive pages.
+  class Client {
+   public:
+    virtual ~Client();
+
+    // Callback called by the archiver upon successful creation of the archive.
+    virtual void OnCreateArchiveSuccess(const Request& request,
+                                        const base::FilePath& file_path) = 0;
+    // Callback called by the archiver when it fails to create the archive.
+    virtual void OnCreateArchiveFailure(const Request& request) = 0;

[Dmitry Titov, 2015/06/11 18:35:32]

What about returning some sort of error? I'm thinking about the mock where we
will do "Could not save the page because there is no available memory on the
device", as opposite to other errors. Since there is a file operation involved,
I think at least a set of { DEVICE_IS_FULL, CANCELLED, UNKNOWN_ERROR } is
needed, likely grow in the future.

[fgorski, 2015/06/11 23:30:02]

Done.

+
+   protected:
+    Client();
+  };
+
+  OfflinePageArchiver();
+  virtual ~OfflinePageArchiver();
+
+  // Starts creating the archive. Will pass result by calling methods on the
+  // passed in client.

[Dmitry Titov, 2015/06/11 18:35:32]

It is a good place to add comment about 'suggested_file_name' (as for why it is
suggested)

[fgorski, 2015/06/11 23:30:02]

Dropped the parameter per offline discussion.

+  virtual Request CreateArchive(

[Dmitry Titov, 2015/06/11 18:35:32]

I think you want to return a pointer or ref to Request... Also, who owns it?

[fgorski, 2015/06/11 23:30:02]

Done.

+      const GURL& url,
+      const std::string& suggested_file_name,
+      Client* client) = 0;
+  // Cancels an in progress request to archive a page.
+  virtual void CancelRequest(const Request& request) = 0;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ARCHIVER_H_