[Offline Pages] Remove expired requests from the queue.

components/offline_pages/background/request_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_BACKGROUND_REQUEST_NOTIFIER_H_
+#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_NOTIFIER_H_
+
+namespace offline_pages {
+
+class SavePageRequest;
+
+class RequestNotifier {
+ public:
+  // Status to return for failed notifications.
+  // TODO(petewil): Can we find a better name for this enum?
+  enum class SavePageStatus {
+    SUCCESS,
+    PRERENDER_FAILURE,
+    FOREGROUND_CANCELED,
+    SAVE_FAILED,
+    EXPIRED,
+    RETRY_COUNT_EXCEEDED,
+    REMOVED,
+  };
+
+  // Notifies observers that |request| has been added.
+  virtual void NotifyAdded(const SavePageRequest& request) = 0;
+
+  // Notifies observers that |request| has been completed with |status|.
+  virtual void NotifyCompleted(const SavePageRequest& request,
+                               SavePageStatus status) = 0;
+
+  // Notifies observers that |request| has been changed.
+  virtual void NotifyChanged(const SavePageRequest& request) = 0;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_NOTIFIER_H_