Migrate part of the BackgroundFetchJobController to the UI thread

content/browser/background_fetch/background_fetch_job_controller.h

 // Copyright 2017 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 CONTENT_BROWSER_BACKGROUND_FETCH_BACKGROUND_FETCH_JOB_CONTROLLER_H_
 #define CONTENT_BROWSER_BACKGROUND_FETCH_BACKGROUND_FETCH_JOB_CONTROLLER_H_
 
 #include <memory>
 #include <string>
 #include <unordered_map>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/optional.h"
 #include "content/browser/background_fetch/background_fetch_registration_id.h"
 #include "content/browser/background_fetch/background_fetch_request_info.h"
 #include "content/common/background_fetch/background_fetch_types.h"
 #include "content/common/content_export.h"
-#include "content/public/browser/download_item.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace net {
+class URLRequestContextGetter;
+}
 
 namespace content {
 
 class BackgroundFetchDataManager;
 class BrowserContext;
-class StoragePartition;
 
 // The JobController will be responsible for coordinating communication with the
 // DownloadManager. It will get requests from the DataManager and dispatch them
 // to the DownloadManager. It lives entirely on the IO thread.
-class CONTENT_EXPORT BackgroundFetchJobController
-    : public DownloadItem::Observer {
+class CONTENT_EXPORT BackgroundFetchJobController {
  public:
   enum class State { INITIALIZED, FETCHING, ABORTED, COMPLETED };
 
   using CompletedCallback =
       base::OnceCallback<void(BackgroundFetchJobController*)>;
 
   BackgroundFetchJobController(
       const BackgroundFetchRegistrationId& registration_id,
       const BackgroundFetchOptions& options,
+      BackgroundFetchDataManager* data_manager,
       BrowserContext* browser_context,
-      StoragePartition* storage_partition,
-      BackgroundFetchDataManager* data_manager,
+      scoped_refptr<net::URLRequestContextGetter> request_context,
       CompletedCallback completed_callback);
-  ~BackgroundFetchJobController() override;
+  ~BackgroundFetchJobController();
 
   // Starts fetching the |initial_fetches|. The controller will continue to
   // fetch new content until all requests have been handled.
   void Start(std::vector<BackgroundFetchRequestInfo> initial_requests);
 
   // Updates the representation of this Background Fetch in the user interface
   // to match the given |title|.
   void UpdateUI(const std::string& title);
 
   // Immediately aborts this Background Fetch by request of the developer.
   void Abort();
 
   // Returns the current state of this Job Controller.
   State state() const { return state_; }
 
   // Returns the registration id for which this job is fetching data.
   const BackgroundFetchRegistrationId& registration_id() const {
     return registration_id_;
   }
 
   // Returns the options with which this job is fetching data.
   const BackgroundFetchOptions& options() const { return options_; }
 
-  // DownloadItem::Observer methods.
-  void OnDownloadUpdated(DownloadItem* item) override;
-  void OnDownloadDestroyed(DownloadItem* item) override;
+ private:
+  class Core;
 
- private:
   // Requests the download manager to start fetching |request|.
   void StartRequest(const BackgroundFetchRequestInfo& request);
 
-  // Called when the request identified by |request_index| has been started.
-  // The |download_item| continues to be owned by the download system. The
-  // |interrupt_reason| will indicate when a request could not be started.
+  // Called when the given |request| has started fetching, after having been
+  // assigned the |download_guid| by the download system.
   void DidStartRequest(const BackgroundFetchRequestInfo& request,
-                       DownloadItem* download_item,
-                       DownloadInterruptReason interrupt_reason);
+                       const std::string& download_guid);
+
+  // Called when the given |request| has been completed.
+  void DidCompleteRequest(const BackgroundFetchRequestInfo& request);
 
   // Called when a completed download has been marked as such in the DataManager
   // and the next request, if any, has been read from storage.
   void DidGetNextRequest(
       const base::Optional<BackgroundFetchRequestInfo>& request);
 
   // The registration id on behalf of which this controller is fetching data.
   BackgroundFetchRegistrationId registration_id_;
 
   // Options for the represented background fetch registration.
   BackgroundFetchOptions options_;
 
   // The current state of this Job Controller.
   State state_ = State::INITIALIZED;
 
-  // Map from DownloadItem* to the request info for the in-progress downloads.
-  std::unordered_map<DownloadItem*, BackgroundFetchRequestInfo> downloads_;
-
-  // Number of outstanding acknowledgements we expect to get from the
-  // DataManager about
-  int pending_completed_file_acknowledgements_ = 0;
-
-  // The BrowserContext that indirectly owns us.
-  BrowserContext* browser_context_;
-
-  // Pointer to the storage partition. This object is owned by the partition
-  // (through a sequence of other classes).
-  StoragePartition* storage_partition_;
+  // Inner core of this job controller which lives on the UI thread.
+  std::unique_ptr<Core, BrowserThread::DeleteOnUIThread> ui_core_;
+  base::WeakPtr<Core> ui_core_ptr_;
 
   // The DataManager's lifetime is controlled by the BackgroundFetchContext and
   // will be kept alive until after the JobController is destroyed.
   BackgroundFetchDataManager* data_manager_;
 
+  // Number of outstanding acknowledgements we still expect to receive.
+  int pending_completed_file_acknowledgements_ = 0;
+
   // Callback for when all fetches have been completed.
   CompletedCallback completed_callback_;
 
   base::WeakPtrFactory<BackgroundFetchJobController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundFetchJobController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BACKGROUND_FETCH_BACKGROUND_FETCH_JOB_CONTROLLER_H_