[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

Index: chrome/browser/android/offline_pages/background_loader_offliner.h
diff --git a/chrome/browser/android/offline_pages/background_loader_offliner.h b/chrome/browser/android/offline_pages/background_loader_offliner.h
index 9be2d75cab48f40d57158d5c8ff83a478a587bd9..207911e2d4c3665539c23d123adf74f1de6ce138 100644
--- a/chrome/browser/android/offline_pages/background_loader_offliner.h
+++ b/chrome/browser/android/offline_pages/background_loader_offliner.h
@@ -62,8 +62,8 @@ class BackgroundLoaderOffliner : public Offliner,
   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;
@@ -74,6 +74,12 @@ class BackgroundLoaderOffliner : public Offliner,
   // 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);