Reload offline version on load failure

ios/chrome/browser/reading_list/reading_list_web_state_observer.h

Index: ios/chrome/browser/reading_list/reading_list_web_state_observer.h
diff --git a/ios/chrome/browser/reading_list/reading_list_web_state_observer.h b/ios/chrome/browser/reading_list/reading_list_web_state_observer.h
index 47fcfb6f9aa4c0075e442c5ac0b852bb6dfc376f..d527bd4d360c7a51082aba3db77200ea61bc33ae 100644
--- a/ios/chrome/browser/reading_list/reading_list_web_state_observer.h
+++ b/ios/chrome/browser/reading_list/reading_list_web_state_observer.h
@@ -12,6 +12,17 @@
 
 class ReadingListModel;
 
+@protocol ReadingListWebStateObserverDelegate
+
+// Tells the delegate the the loading of the online version failed and the
+// offline version must be displayed.
+- (void)displayOfflineVersionForURL:(const GURL&)URL;
+
+@end
+
+typedef id<ReadingListWebStateObserverDelegate>
+    ReadingListWebStateObserverDelegateType;
+
 // Observes the loading of pages coming from the reading list, determines
 // whether loading an offline version of the page is needed, and actually
 // trigger the loading of the offline page (if possible).
@@ -19,7 +30,8 @@ class ReadingListWebStateObserver : public web::WebStateObserver {
  public:
   static ReadingListWebStateObserver* FromWebState(
       web::WebState* web_state,
-      ReadingListModel* reading_list_model);
+      ReadingListModel* reading_list_model,
+      ReadingListWebStateObserverDelegateType delegate);
 
   ~ReadingListWebStateObserver() override;
 
@@ -33,7 +45,8 @@ class ReadingListWebStateObserver : public web::WebStateObserver {
 
  private:
   ReadingListWebStateObserver(web::WebState* web_state,
-                              ReadingListModel* reading_list_model);
+                              ReadingListModel* reading_list_model,
+                              ReadingListWebStateObserverDelegateType delegate);
 
   // Looks at the loading percentage. If less than 15%, attemps to load the
   // offline version of that page.
@@ -46,15 +59,18 @@ class ReadingListWebStateObserver : public web::WebStateObserver {
   void StopCheckingProgress();
 
   // WebContentsObserver implementation.
-  void DidStopLoading() override;
+  void DidStartLoading() override;
   void PageLoaded(
       web::PageLoadCompletionStatus load_completion_status) override;
   void WebStateDestroyed() override;
 
+  void LoadReadingListDistilled();
+
   ReadingListModel* reading_list_model_;
   std::unique_ptr<base::Timer> timer_;
   GURL pending_url_;
   int try_number_;
+  ReadingListWebStateObserverDelegateType delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadingListWebStateObserver);
 };