Load offline page if reading list entry takes more than 1s to load.

ios/chrome/browser/reading_list/reading_list_model_impl.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 IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_IMPL_H_
 #define IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_IMPL_H_
 
 #include <memory>
 
 #include "components/keyed_service/core/keyed_service.h"
 #include "ios/chrome/browser/reading_list/reading_list_entry.h"
 #include "ios/chrome/browser/reading_list/reading_list_model.h"
 
 class ReadingListModelStorage;
 
 // Concrete implementation of a reading list model using in memory lists.
 class ReadingListModelImpl : public ReadingListModel, public KeyedService {
  public:
   // Initialize a ReadingListModelImpl to load and save data in
   // |persistence_layer|.
   ReadingListModelImpl(std::unique_ptr<ReadingListModelStorage> storage_layer);
 
   // Initialize a ReadingListModelImpl without persistence. Data will not be
   // persistent across sessions.
   ReadingListModelImpl();
 
   ~ReadingListModelImpl() override;
+
+  // KeyedService implementation.
   void Shutdown() override;
 
+  // ReadingListModel implementation.
   bool loaded() const override;
 
   size_t unread_size() const override;
   size_t read_size() const override;
 
   bool HasUnseenEntries() const override;
   void ResetUnseenEntries() override;
 
-  // Returns a specific entry.
-  const ReadingListEntry& GetUnreadEntryAtIndex(size_t index) const override;
-  const ReadingListEntry& GetReadEntryAtIndex(size_t index) const override;
+  const ReadingListEntry* GetUnreadEntryAtIndex(size_t index) const override;
+  const ReadingListEntry* GetReadEntryAtIndex(size_t index) const override;
+  const ReadingListEntry* GetEntryFromURL(const GURL& gurl) const override;
 
   bool CallbackEntryURL(
       const GURL& url,
       base::Callback<void(const ReadingListEntry&)> callback) const override;
 
   void RemoveEntryByUrl(const GURL& url) override;
 
   const ReadingListEntry& AddEntry(const GURL& url,
                                    const std::string& title) override;
 
@@ skipping 15 matching lines @@
   ReadingListEntries unread_;
   ReadingListEntries read_;
   std::unique_ptr<ReadingListModelStorage> storageLayer_;
   bool hasUnseen_;
   bool loaded_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadingListModelImpl);
 };
 
 #endif  // IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_MEMORY_H_