[Offline pages] Create offliner that uses background loader

chrome/browser/android/offline_pages/background_loader_offliner.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 CHROME_BROWSER_ANDROID_OFFLINE_PAGES_BACKGROUND_LOADER_OFFLINER_H_
+#define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_BACKGROUND_LOADER_OFFLINER_H_
+
+#include <memory>
+
+#include "base/android/application_status_listener.h"
+#include "base/memory/weak_ptr.h"
+#include "components/offline_pages/content/background_loader/background_loader_contents.h"
+#include "components/offline_pages/core/background/offliner.h"
+#include "components/offline_pages/core/offline_page_types.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace content {
+class BrowserContext;
+}  // namespace content
+
+namespace offline_pages {
+
+class OfflinerPolicy;
+class OfflinePageModel;
+
+// An Offliner implementation that attempts client-side rendering and saving
+// of an offline page. It uses the BackgroundLoader to load the page and the
+// OfflinePageModel to save it. Only one request may be active at a time.
+class BackgroundLoaderOffliner : public Offliner,
+                                 public content::WebContentsObserver {
+ public:
+  BackgroundLoaderOffliner(content::BrowserContext* browser_context,
+                           const OfflinerPolicy* policy,
+                           OfflinePageModel* offline_page_model);
+  ~BackgroundLoaderOffliner() override;
+
+  // Offliner implementation.
+  bool LoadAndSave(const SavePageRequest& request,
+                   const CompletionCallback& callback) override;
+  void Cancel() override;
+
+  // WebContentsObserver implementation.
+  void DidStopLoading() override;
+
+ protected:
+  // Called to reset internal loader and observer state.
+  virtual void ResetState();
+
+ private:
+  friend class TestBackgroundLoaderOffliner;
+
+  enum SaveState { NONE, SAVING, DELETE_AFTER_SAVE };
+
+  // Called when the page has been saved.
+  void OnPageSaved(SavePageResult save_result, int64_t offline_id);
+
+  // Called when application state has changed.
+  void OnApplicationStateChange(
+      base::android::ApplicationState application_state);
+
+  std::unique_ptr<background_loader::BackgroundLoaderContents> loader_;
+  // Not owned.
+  content::BrowserContext* browser_context_;
+  // Not owned.
+  OfflinePageModel* offline_page_model_;
+  // Tracks pending request, if any.
+  std::unique_ptr<SavePageRequest> pending_request_;
+  // Callback when pending request completes.
+  CompletionCallback completion_callback_;
+  // ApplicationStatusListener to monitor if Chrome moves to the foreground.
+  std::unique_ptr<base::android::ApplicationStatusListener> app_listener_;
+  // Whether we are on a low-end device.
+  bool is_low_end_device_;
+  // Save state.
+  SaveState save_state_;
+
+  base::WeakPtrFactory<BackgroundLoaderOffliner> weak_ptr_factory_;
+  DISALLOW_COPY_AND_ASSIGN(BackgroundLoaderOffliner);
+};
+
+}  // namespace offline_pages
+#endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_BACKGROUND_LOADER_OFFLINER_H_