[Offline pages] Stop observing web contents and reset to null after use. Only create a new web cont…

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"
@@ skipping 44 matching lines @@
       content::NavigationHandle* navigation_handle) override;
 
   // SnapshotController::Client implementation.
   void StartSnapshot() override;
 
   void SetSnapshotControllerForTest(
       std::unique_ptr<SnapshotController> controller);
   void OnNetworkBytesChanged(int64_t bytes);
 
  protected:
-  // Called to reset internal loader and observer state.
-  virtual void ResetState();
+  // Called to reset the loader.
+  virtual void ResetLoader();
 
  private:
   friend class TestBackgroundLoaderOffliner;
 
   enum SaveState { NONE, SAVING, DELETE_AFTER_SAVE };
   enum PageLoadState { SUCCESS, RETRIABLE, NONRETRIABLE, DELAY_RETRY };
 
   // Called when the page has been saved.
   void OnPageSaved(SavePageResult save_result, int64_t offline_id);
 
+  // Called to reset internal loader and observer state.
+  void ResetState();
+
+  // Called to attach 'this' as the observer to the loader.
+  void AttachObservers();
+
   // Called when application state has changed.
   void OnApplicationStateChange(
       base::android::ApplicationState application_state);
   void HandleApplicationStateChangeCancel(const SavePageRequest& request,
                                           int64_t offline_id);
 
   std::unique_ptr<background_loader::BackgroundLoaderContents> loader_;
   // Not owned.
   content::BrowserContext* browser_context_;
   // Not owned.
@@ skipping 20 matching lines @@
 
   // Callback for cancel.
   CancelCallback cancel_callback_;
 
   base::WeakPtrFactory<BackgroundLoaderOffliner> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(BackgroundLoaderOffliner);
 };
 
 }  // namespace offline_pages
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_BACKGROUND_LOADER_OFFLINER_H_