Add the request picker and a unit test

components/offline_pages/background/request_coordinator.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_COORDINATOR_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 
 #include <memory>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/offline_pages/background/offliner.h"
 #include "components/offline_pages/background/request_queue.h"
 #include "url/gurl.h"
 
 namespace offline_pages {
 
 struct ClientId;
 class OfflinerPolicy;
 class OfflinerFactory;
 class Offliner;
+class RequestPicker;
 class SavePageRequest;
 class Scheduler;
 
 // Coordinates queueing and processing save page later requests.
-class RequestCoordinator :
-    public KeyedService,
-    public base::SupportsWeakPtr<RequestCoordinator>  {
+class RequestCoordinator : public KeyedService {
  public:
   // Callback to report when the processing of a triggered task is complete.
   typedef base::Callback<void()> ProcessingDoneCallback;
+  typedef base::Callback<void(const SavePageRequest& request)>
+      RequestPickedCallback;
+  typedef base::Callback<void()> RequestQueueEmptyCallback;
 
   RequestCoordinator(std::unique_ptr<OfflinerPolicy> policy,
                      std::unique_ptr<OfflinerFactory> factory,
                      std::unique_ptr<RequestQueue> queue,
                      std::unique_ptr<Scheduler> scheduler);
 
   ~RequestCoordinator() override;
 
   // Queues |request| to later load and save when system conditions allow.
   // Returns true if the page could be queued successfully.
@@ skipping 17 matching lines @@
 
   // Returns the status of the most recent offlining.
   Offliner::RequestStatus last_offlining_status() {
     return last_offlining_status_;
   }
 
  private:
   void AddRequestResultCallback(RequestQueue::AddRequestResult result,
                                 const SavePageRequest& request);
 
+  // Callback from the request picker when it has chosen our next request.
+  void RequestPicked(const SavePageRequest& request);
+
+  // Callback from the request picker when no more requests are in the queue.
+  void RequestQueueEmpty();
+
   void SendRequestToOffliner(const SavePageRequest& request);
 
   void OfflinerDoneCallback(const SavePageRequest& request,
                             Offliner::RequestStatus status);
 
   // RequestCoordinator takes over ownership of the policy
   std::unique_ptr<OfflinerPolicy> policy_;
   // OfflinerFactory.  Used to create offline pages. Owned.
   std::unique_ptr<OfflinerFactory> factory_;
   // RequestQueue.  Used to store incoming requests. Owned.
   std::unique_ptr<RequestQueue> queue_;
   // Scheduler. Used to request a callback when network is available.  Owned.
   std::unique_ptr<Scheduler> scheduler_;
   // Status of the most recent offlining.
   Offliner::RequestStatus last_offlining_status_;
+  // Class to choose which request to schedule next
+  std::unique_ptr<RequestPicker> picker_;
+  // Allows us to pass a weak pointer to callbacks.
+  base::WeakPtrFactory<RequestCoordinator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestCoordinator);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_