Split the RequestPicker task into two separate tasks.

components/offline_pages/background/cleanup_task.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_CLEANUP_TASK_H_
+#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_CLEANUP_TASK_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/memory/weak_ptr.h"
+#include "components/offline_pages/background/request_queue_results.h"
+#include "components/offline_pages/background/save_page_request.h"
+#include "components/offline_pages/core/task.h"
+
+namespace offline_pages {
+
+class OfflinerPolicy;
+class RequestCoordinatorEventLogger;
+class RequestNotifier;
+class RequestQueueStore;
+
+class CleanupTask : public Task {
+ public:
+  CleanupTask(RequestQueueStore* store,
+              OfflinerPolicy* policy,
+              RequestNotifier* notifier,
+              RequestCoordinatorEventLogger* logger,
+              int64_t current_request_id);

[dougarnett, 2016/12/05 21:27:45]

Maybe active_request_id or excluded_request_id as "current" may not clear in
this context as being current in an offliner.

Or perhaps be good to comment what this parameter means.

Also, seems like you ought to mention invalid id value.

[Pete Williamson, 2016/12/06 00:25:38]

Removed the parameter, since I took FGorski's suggestion to check the state
instead as being more scalable.  That meant I also removed the use of the
invalid ID value elsewhere.

+  ~CleanupTask() override;
+
+  // TaskQueue::Task implementation, starts the async chain
+  void Run() override;
+
+ private:
+  // Step 1. get results from the store
+  void GetRequests();
+
+  // Step 2. Prune stale requests
+  void Prune(bool success,
+             std::vector<std::unique_ptr<SavePageRequest>> requests);
+
+  // Step 3. Send delete notifications for the expired requests.
+  void OnRequestsExpired(std::unique_ptr<UpdateRequestsResult> result);
+
+  // Build a list of IDs whose request has expired.
+  void GetExpiredRequestIds(
+      std::vector<std::unique_ptr<SavePageRequest>> requests,
+      std::vector<int64_t>* expired_request_ids);
+
+  // Member variables, all pointers are not owned here.
+  RequestQueueStore* store_;
+  OfflinerPolicy* policy_;
+  RequestNotifier* notifier_;
+  RequestCoordinatorEventLogger* event_logger_;
+  int64_t current_request_id_;
+  // Allows us to pass a weak pointer to callbacks.
+  base::WeakPtrFactory<CleanupTask> weak_ptr_factory_;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_CLEANUP_TASK_H_