Move all components/offline_pages/ files into component/offline_pages/core

components/offline_pages/downloads/offline_page_download_notifier.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_OFFLINE_PAGES_DOWNLOADS_OFFLINE_PAGE_DOWNLOAD_NOTIFIER_H_
-#define COMPONENTS_OFFLINE_PAGES_DOWNLOADS_OFFLINE_PAGE_DOWNLOAD_NOTIFIER_H_
-
-#include "components/offline_pages/downloads/download_ui_item.h"
-
-namespace offline_pages {
-
-struct OfflinePageDownloadNotifier {
- public:
-  virtual ~OfflinePageDownloadNotifier() = default;
-
-  // Reports that |item| has completed successfully.
-  virtual void NotifyDownloadSuccessful(const DownloadUIItem& item) = 0;
-
-  // Reports that |item| has completed unsuccessfully.
-  virtual void NotifyDownloadFailed(const DownloadUIItem& item) = 0;
-
-  // Reports that |item| is active and possibly making progress.
-  virtual void NotifyDownloadProgress(const DownloadUIItem& item) = 0;
-
-  // Reports that |item| has been paused (and so it is not active).
-  virtual void NotifyDownloadPaused(const DownloadUIItem& item) = 0;
-
-  // Reports that any progress on |item| has been interrupted. It is pending
-  // or available for another attempt when conditions allows.
-  virtual void NotifyDownloadInterrupted(const DownloadUIItem& item) = 0;
-
-  // Reports that |item| has been canceled.
-  virtual void NotifyDownloadCanceled(const DownloadUIItem& item) = 0;
-};
-
-}  // namespace offline_pages
-
-#endif  // COMPONENTS_OFFLINE_PAGES_DOWNLOADS_OFFLINE_PAGE_DOWNLOAD_NOTIFIER_H_