[OfflinePages] Call NotifyInterrupted for pending requests

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_